diff --git a/src/utils.ts b/src/utils.ts
index a3f99779..9e3345e0 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -14,6 +14,7 @@ const PROTOCOL_RELATIVE_REGEX = /^([/\\]\s*){2,}[^/\\]/;
 const PROTOCOL_SCRIPT_RE = /^[\s\0]*(blob|data|javascript|vbscript):$/i;
 const TRAILING_SLASH_RE = /\/$|\/\?|\/#/;
 const JOIN_LEADING_SLASH_RE = /^\.?\//;
+const JOIN_LAST_SEGMENT_RE = /(?:^|\/)[^/]*\/?$/;
 
 /**
  * Check if a path starts with `./` or `../`.
@@ -323,9 +324,17 @@ export function joinURL(base: string, ...input: string[]): string {
 
   for (const segment of input.filter((url) => isNonEmptyURL(url))) {
     if (url) {
-      // TODO: Handle .. when joining
-      const _segment = segment.replace(JOIN_LEADING_SLASH_RE, "");
-      url = withTrailingSlash(url) + _segment;
+      const hasAbsoluteBase = url.startsWith("/");
+      let _segment = segment;
+      _segment = _segment.replace(JOIN_LEADING_SLASH_RE, "");
+      while (url.length > 0 && _segment.startsWith("../")) {
+        url = url.replace(JOIN_LAST_SEGMENT_RE, "");
+        _segment = _segment.slice(3).replace(JOIN_LEADING_SLASH_RE, "");
+      }
+      url =
+        !url && (!hasAbsoluteBase || _segment.startsWith("../"))
+          ? _segment
+          : withTrailingSlash(url) + _segment;
     } else {
       url = segment;
     }
diff --git a/test/join.test.ts b/test/join.test.ts
index e7c400bb..0135200a 100644
--- a/test/join.test.ts
+++ b/test/join.test.ts
@@ -7,9 +7,21 @@ describe("joinURL", () => {
     { input: ["/"], out: "/" },
     // eslint-disable-next-line unicorn/no-null
     { input: [null, "./"], out: "./" },
+    { input: ["./", "a"], out: "./a" },
+    { input: ["./a", "./b"], out: "./a/b" },
     { input: ["/a"], out: "/a" },
     { input: ["a", "b"], out: "a/b" },
     { input: ["/", "/b"], out: "/b" },
+    { input: ["/a", "../b"], out: "/b" },
+    { input: ["../a", "../b"], out: "../b" },
+    { input: ["../a", "./../b"], out: "../b" },
+    { input: ["../a", "./../../b"], out: "b" },
+    { input: ["../a", "../../../b"], out: "../b" },
+    { input: ["../a", "../../../../b"], out: "../../b" },
+    { input: ["../a/", "../b"], out: "../b" },
+    { input: ["/a/b/c", "../../d"], out: "/a/d" },
+    { input: ["/c", "../../d"], out: "../d" },
+    { input: ["/c", ".././../d"], out: "../d" },
     { input: ["a", "b/", "c"], out: "a/b/c" },
     { input: ["a", "b/", "/c"], out: "a/b/c" },
     { input: ["/", "./"], out: "/" },