diff --git a/nuget/lib/dependabot/nuget/update_checker/nupkg_fetcher.rb b/nuget/lib/dependabot/nuget/update_checker/nupkg_fetcher.rb
index d73e8e3182f..b9f53f9d1eb 100644
--- a/nuget/lib/dependabot/nuget/update_checker/nupkg_fetcher.rb
+++ b/nuget/lib/dependabot/nuget/update_checker/nupkg_fetcher.rb
@@ -1,23 +1,43 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "nokogiri"
-require "zip"
 require "stringio"
+require "sorbet-runtime"
+require "zip"
+
 require "dependabot/nuget/http_response_helpers"
 
 module Dependabot
   module Nuget
     class NupkgFetcher
+      extend T::Sig
+
       require_relative "repository_finder"
 
+      sig do
+        params(
+          dependency_urls: T::Array[T::Hash[Symbol, String]],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(String))
+      end
       def self.fetch_nupkg_buffer(dependency_urls, package_id, package_version)
         # check all repositories for the first one that has the nupkg
-        dependency_urls.reduce(nil) do |nupkg_buffer, repository_details|
+        dependency_urls.reduce(T.let(nil, T.nilable(String))) do |nupkg_buffer, repository_details|
           nupkg_buffer || fetch_nupkg_buffer_from_repository(repository_details, package_id, package_version)
         end
       end
 
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: T.nilable(String),
+          package_version: T.nilable(String)
+        )
+          .returns(T.nilable(String))
+      end
       def self.fetch_nupkg_url_from_repository(repository_details, package_id, package_version)
         return unless package_id && package_version && !package_version.empty?
 
@@ -35,6 +55,14 @@ def self.fetch_nupkg_url_from_repository(repository_details, package_id, package
         package_url
       end
 
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(String))
+      end
       def self.fetch_nupkg_buffer_from_repository(repository_details, package_id, package_version)
         package_url = fetch_nupkg_url_from_repository(repository_details, package_id, package_version)
         return unless package_url
@@ -43,6 +71,14 @@ def self.fetch_nupkg_buffer_from_repository(repository_details, package_id, pack
         fetch_stream(package_url, auth_header)
       end
 
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(String))
+      end
       def self.get_nuget_v3_package_url(repository_details, package_id, package_version)
         base_url = repository_details[:base_url]
         unless base_url
@@ -57,15 +93,23 @@ def self.get_nuget_v3_package_url(repository_details, package_id, package_versio
 
       # rubocop:disable Metrics/CyclomaticComplexity
       # rubocop:disable Metrics/PerceivedComplexity
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(String))
+      end
       def self.get_nuget_v3_package_url_from_search(repository_details, package_id, package_version)
         search_url = repository_details[:search_url]
         return nil unless search_url
 
         # get search result
         search_result_response = fetch_url(search_url, repository_details)
-        return nil unless search_result_response.status == 200
+        return nil unless search_result_response&.status == 200
 
-        search_response_body = HttpResponseHelpers.remove_wrapping_zero_width_chars(search_result_response.body)
+        search_response_body = HttpResponseHelpers.remove_wrapping_zero_width_chars(T.must(search_result_response).body)
         search_results = JSON.parse(search_response_body)
 
         # find matching package and version
@@ -90,15 +134,23 @@ def self.get_nuget_v3_package_url_from_search(repository_details, package_id, pa
       # rubocop:enable Metrics/PerceivedComplexity
       # rubocop:enable Metrics/CyclomaticComplexity
 
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(String))
+      end
       def self.get_nuget_v2_package_url(repository_details, package_id, package_version)
         # get package XML
         base_url = repository_details[:base_url].delete_suffix("/")
         package_url = "#{base_url}/Packages(Id='#{package_id}',Version='#{package_version}')"
         response = fetch_url(package_url, repository_details)
-        return nil unless response.status == 200
+        return nil unless response&.status == 200
 
         # find relevant element
-        doc = Nokogiri::XML(response.body)
+        doc = Nokogiri::XML(T.must(response).body)
         doc.remove_namespaces!
 
         content_element = doc.xpath("/entry/content")
@@ -106,6 +158,14 @@ def self.get_nuget_v2_package_url(repository_details, package_id, package_versio
         nupkg_url
       end
 
+      sig do
+        params(
+          stream_url: String,
+          auth_header: T::Hash[String, String],
+          max_redirects: Integer
+        )
+          .returns(T.nilable(String))
+      end
       def self.fetch_stream(stream_url, auth_header, max_redirects = 5)
         current_url = stream_url
         current_redirects = 0
@@ -128,17 +188,25 @@ def self.fetch_stream(stream_url, auth_header, max_redirects = 5)
             current_redirects += 1
             return nil if current_redirects > max_redirects
 
-            current_url = response.headers["Location"]
+            current_url = T.must(response.headers["Location"])
           else
             return nil
           end
         end
       end
 
+      sig do
+        params(
+          url: String,
+          repository_details: T::Hash[Symbol, T.untyped]
+        )
+          .returns(T.nilable(Excon::Response))
+      end
       def self.fetch_url(url, repository_details)
         fetch_url_with_auth(url, repository_details.fetch(:auth_header))
       end
 
+      sig { params(url: String, auth_header: T::Hash[T.any(String, Symbol), T.untyped]).returns(Excon::Response) }
       def self.fetch_url_with_auth(url, auth_header)
         cache = CacheManager.cache("nupkg_fetcher_cache")
         cache[url] ||= Dependabot::RegistryClient.get(
diff --git a/nuget/lib/dependabot/nuget/update_checker/nuspec_fetcher.rb b/nuget/lib/dependabot/nuget/update_checker/nuspec_fetcher.rb
index 76fdbac5326..6e2c11faa64 100644
--- a/nuget/lib/dependabot/nuget/update_checker/nuspec_fetcher.rb
+++ b/nuget/lib/dependabot/nuget/update_checker/nuspec_fetcher.rb
@@ -1,23 +1,42 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "nokogiri"
-require "zip"
 require "stringio"
+require "sorbet-runtime"
+require "zip"
 
 module Dependabot
   module Nuget
     class NuspecFetcher
+      extend T::Sig
+
       require_relative "nupkg_fetcher"
       require_relative "repository_finder"
 
+      sig do
+        params(
+          dependency_urls: T::Array[T::Hash[Symbol, String]],
+          package_id: String,
+          package_version: String
+        )
+          .returns(T.nilable(Nokogiri::XML::Document))
+      end
       def self.fetch_nuspec(dependency_urls, package_id, package_version)
         # check all repositories for the first one that has the nuspec
-        dependency_urls.reduce(nil) do |nuspec_xml, repository_details|
+        dependency_urls.reduce(T.let(nil, T.nilable(Nokogiri::XML::Document))) do |nuspec_xml, repository_details|
           nuspec_xml || fetch_nuspec_from_repository(repository_details, package_id, package_version)
         end
       end
 
+      sig do
+        params(
+          repository_details: T::Hash[Symbol, T.untyped],
+          package_id: T.nilable(String),
+          package_version: T.nilable(String)
+        )
+          .returns(T.nilable(Nokogiri::XML::Document))
+      end
       def self.fetch_nuspec_from_repository(repository_details, package_id, package_version)
         return unless package_id && package_version && !package_version.empty?
 
@@ -55,6 +74,7 @@ def self.fetch_nuspec_from_repository(repository_details, package_id, package_ve
         nuspec_xml
       end
 
+      sig { params(feed_url: String).returns(T::Boolean) }
       def self.feed_supports_nuspec_download?(feed_url)
         feed_regexs = [
           # nuget
@@ -67,6 +87,7 @@ def self.feed_supports_nuspec_download?(feed_url)
         feed_regexs.any? { |reg| reg.match(feed_url) }
       end
 
+      sig { params(zip_stream: String, package_id: String).returns(T.nilable(String)) }
       def self.extract_nuspec(zip_stream, package_id)
         Zip::File.open_buffer(zip_stream) do |zip|
           nuspec_entry = zip.find { |entry| entry.name == "#{package_id}.nuspec" }
@@ -75,6 +96,7 @@ def self.extract_nuspec(zip_stream, package_id)
         nil
       end
 
+      sig { params(string: String).returns(String) }
       def self.remove_invalid_characters(string)
         string.dup
               .force_encoding(Encoding::UTF_8)
diff --git a/nuget/lib/dependabot/nuget/update_checker/requirements_updater.rb b/nuget/lib/dependabot/nuget/update_checker/requirements_updater.rb
index 6e1fca47df0..fe600921c1c 100644
--- a/nuget/lib/dependabot/nuget/update_checker/requirements_updater.rb
+++ b/nuget/lib/dependabot/nuget/update_checker/requirements_updater.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 #######################################################################
@@ -6,6 +6,8 @@
 # https://docs.microsoft.com/en-us/nuget/reference/package-versioning #
 #######################################################################
 
+require "sorbet-runtime"
+
 require "dependabot/update_checkers/base"
 require "dependabot/nuget/version"
 
@@ -13,14 +15,25 @@ module Dependabot
   module Nuget
     class UpdateChecker < Dependabot::UpdateCheckers::Base
       class RequirementsUpdater
+        extend T::Sig
+
+        sig do
+          params(
+            requirements: T::Array[T::Hash[Symbol, T.untyped]],
+            latest_version: T.nilable(T.any(String, Dependabot::Nuget::Version)),
+            source_details: T.nilable(T::Hash[Symbol, T.untyped])
+          )
+            .void
+        end
         def initialize(requirements:, latest_version:, source_details:)
           @requirements = requirements
           @source_details = source_details
           return unless latest_version
 
-          @latest_version = version_class.new(latest_version)
+          @latest_version = T.let(version_class.new(latest_version), Dependabot::Nuget::Version)
         end
 
+        sig { returns(T::Array[T::Hash[Symbol, T.untyped]]) }
         def updated_requirements
           return requirements unless latest_version
 
@@ -52,32 +65,42 @@ def updated_requirements
 
         private
 
-        attr_reader :requirements, :latest_version, :source_details
+        sig { returns(T::Array[T::Hash[Symbol, T.untyped]]) }
+        attr_reader :requirements
+
+        sig { returns(T.nilable(Dependabot::Nuget::Version)) }
+        attr_reader :latest_version
+
+        sig { returns(T.nilable(T::Hash[Symbol, T.untyped])) }
+        attr_reader :source_details
 
+        sig { returns(T.class_of(Dependabot::Nuget::Version)) }
         def version_class
-          Nuget::Version
+          Dependabot::Nuget::Version
         end
 
+        sig { params(req_string: String).returns(String) }
         def update_wildcard_requirement(req_string)
           return req_string if req_string == "*-*"
 
           return req_string if req_string == "*"
 
-          precision = req_string.split("*").first.split(/\.|\-/).count
+          precision = T.must(req_string.split("*").first).split(/\.|\-/).count
           wildcard_section = req_string.partition(/(?=[.\-]\*)/).last
 
-          version_parts = latest_version.segments.first(precision)
+          version_parts = T.must(latest_version).segments.first(precision)
           version = version_parts.join(".")
 
           version + wildcard_section
         end
 
+        sig { returns(T::Hash[Symbol, T.untyped]) }
         def updated_source
           {
             type: "nuget_repo",
-            url: source_details.fetch(:repo_url),
-            nuspec_url: source_details.fetch(:nuspec_url),
-            source_url: source_details.fetch(:source_url)
+            url: source_details&.fetch(:repo_url),
+            nuspec_url: source_details&.fetch(:nuspec_url),
+            source_url: source_details&.fetch(:source_url)
           }
         end
       end