diff --git a/browser/src/Services/Browser/index.tsx b/browser/src/Services/Browser/index.tsx
index d164714dd8..0cf849ea18 100644
--- a/browser/src/Services/Browser/index.tsx
+++ b/browser/src/Services/Browser/index.tsx
@@ -4,7 +4,7 @@
  * Entry point for browser integration plugin
  */
 
-import { ipcRenderer, shell, WebviewTag } from "electron"
+import { shell, WebviewTag } from "electron"
 import * as React from "react"
 
 import * as Oni from "oni-api"
@@ -290,10 +290,6 @@ export const activate = (
         detail: "",
         enabled: isBrowserScrollCommandEnabled,
     })
-
-    ipcRenderer.on("open-oni-browser", (event: string, args: string) => {
-        openUrl(args)
-    })
 }
 
 export const registerAchievements = (achievements: AchievementsManager) => {
diff --git a/browser/src/Services/Configuration/DefaultConfiguration.ts b/browser/src/Services/Configuration/DefaultConfiguration.ts
index 6e0b00b84c..b4ee21ce9d 100644
--- a/browser/src/Services/Configuration/DefaultConfiguration.ts
+++ b/browser/src/Services/Configuration/DefaultConfiguration.ts
@@ -81,6 +81,8 @@ const BaseConfiguration: IConfigurationValues = {
     "experimental.indentLines.bannedFiletypes": [],
     "experimental.markdownPreview.enabled": false,
     "experimental.markdownPreview.autoScroll": true,
+    "experimental.markdownPreview.syntaxHighlights": true,
+    "experimental.markdownPreview.syntaxTheme": "atom-one-dark",
 
     "experimental.neovim.transport": "stdio",
     // TODO: Enable pipe transport for Windows
diff --git a/browser/src/Services/Configuration/IConfigurationValues.ts b/browser/src/Services/Configuration/IConfigurationValues.ts
index ffaa97f878..e37f950fdd 100644
--- a/browser/src/Services/Configuration/IConfigurationValues.ts
+++ b/browser/src/Services/Configuration/IConfigurationValues.ts
@@ -65,6 +65,8 @@ export interface IConfigurationValues {
     // Whether the markdown preview pane should be shown
     "experimental.markdownPreview.enabled": boolean
     "experimental.markdownPreview.autoScroll": boolean
+    "experimental.markdownPreview.syntaxHighlights": boolean
+    "experimental.markdownPreview.syntaxTheme": string
 
     // The transport to use for Neovim
     // Valid values are "stdio" and "pipe"
diff --git a/extensions/oni-plugin-markdown-preview/package.json b/extensions/oni-plugin-markdown-preview/package.json
index a890d11ac3..acd23614c0 100644
--- a/extensions/oni-plugin-markdown-preview/package.json
+++ b/extensions/oni-plugin-markdown-preview/package.json
@@ -23,6 +23,7 @@
     "tbd-dependencies": {
         "marked": "^0.4.0",
         "dompurify": "1.0.2",
+        "highlight.js": "^9.12.0",
         "oni-types": "^0.0.4",
         "oni-api": "^0.0.9"
     },
@@ -31,6 +32,7 @@
         "rimraf": "^2.6.2"
     },
     "tbd-devDependencies": {
+        "@types/highlight.js": "^9.12.2",
         "typescript": "2.5.3",
         "rimraf": "2.6.2"
     }
diff --git a/extensions/oni-plugin-markdown-preview/src/index.tsx b/extensions/oni-plugin-markdown-preview/src/index.tsx
index cf5479ecf3..d87cfdf003 100644
--- a/extensions/oni-plugin-markdown-preview/src/index.tsx
+++ b/extensions/oni-plugin-markdown-preview/src/index.tsx
@@ -1,6 +1,7 @@
 import { EventCallback, IDisposable, IEvent } from "oni-types"
 
 import * as dompurify from "dompurify"
+import * as hljs from "highlight.js"
 import * as marked from "marked"
 import * as Oni from "oni-api"
 import * as React from "react"
@@ -84,6 +85,9 @@ class MarkdownPreview extends React.PureComponent<IMarkdownPreviewProps, IMarkdo
 
     private generateContainerStyle(): string {
         const colors = this.state.colors
+        const syntaxHighlightTheme = this.props.oni.configuration.getValue(
+            "experimental.markdownPreview.syntaxTheme",
+        )
 
         const codeBlockStyle = `
             background: ${colors.codeBackground};
@@ -95,6 +99,8 @@ class MarkdownPreview extends React.PureComponent<IMarkdownPreviewProps, IMarkdo
         `
 
         return `
+            <link rel="stylesheet" href="node_modules/highlight.js/styles/${syntaxHighlightTheme}.css">
+
             <style>
             .oniPluginMarkdownPreviewContainerStyle {
                 padding: 1em 1em 1em 1em;
@@ -143,6 +149,38 @@ class MarkdownPreview extends React.PureComponent<IMarkdownPreviewProps, IMarkdo
         markdownLines.splice(0, 0, generateAnchor(i))
         markdownLines.push(generateAnchor(originalLinesCount - 1))
 
+        const markedOptions = {
+            baseUrl: this.props.oni.workspace.activeWorkspace,
+            highlight(code, lang) {
+                return code
+            },
+        }
+
+        const highlightsEnabled = this.props.oni.configuration.getValue(
+            "experimental.markdownPreview.syntaxHighlights",
+        )
+
+        if (highlightsEnabled) {
+            markedOptions.highlight = (code, lang) => {
+                const languageExists = hljs.getLanguage(lang)
+                const languageNotDefinedOrInvalid =
+                    typeof lang === "undefined" ||
+                    (typeof languageExists === "undefined" && lang !== "nohighlight")
+
+                if (languageNotDefinedOrInvalid) {
+                    return hljs.highlightAuto(code).value
+                }
+
+                if (lang === "nohighlight") {
+                    return code
+                }
+
+                return hljs.highlight(lang, code).value
+            }
+        }
+
+        marked.setOptions(markedOptions)
+
         return marked(markdownLines.join("\n"))
     }
 
diff --git a/main/src/main.ts b/main/src/main.ts
index 6240cbca6b..3aaea3d157 100644
--- a/main/src/main.ts
+++ b/main/src/main.ts
@@ -258,7 +258,7 @@ export function createWindow(
     if (!isDevelopment) {
         currentWindow.webContents.on("will-navigate", (event, url) => {
             event.preventDefault()
-            currentWindow.webContents.send("open-oni-browser", url)
+            currentWindow.webContents.send("execute-command", "browser.openUrl", url)
         })
     }
 
diff --git a/package.json b/package.json
index a6a8c9f55a..ab25de0bbf 100644
--- a/package.json
+++ b/package.json
@@ -699,6 +699,7 @@
         "electron-settings": "^3.1.4",
         "find-up": "2.1.0",
         "fs-extra": "^5.0.0",
+        "highlight.js": "^9.12.0",
         "json5": "^1.0.1",
         "keyboard-layout": "^2.0.13",
         "marked": "^0.4.0",
@@ -734,12 +735,13 @@
         "@types/electron-settings": "^3.1.1",
         "@types/enzyme": "^3.1.8",
         "@types/fs-extra": "^5.0.2",
+        "@types/highlight.js": "^9.12.2",
         "@types/jest": "^22.1.3",
         "@types/jsdom": "11.0.0",
         "@types/json5": "^0.0.29",
         "@types/lodash": "4.14.38",
         "@types/lolex": "2.1.0",
-        "@types/marked": "^0.3.0",
+        "@types/marked": "^0.4.0",
         "@types/minimatch": "3.0.1",
         "@types/minimist": "1.1.29",
         "@types/mkdirp": "0.3.29",
diff --git a/test/ci/MarkdownPreviewTest.tsx b/test/ci/MarkdownPreviewTest.tsx
index fcaf6e83e1..6b4572e1b5 100644
--- a/test/ci/MarkdownPreviewTest.tsx
+++ b/test/ci/MarkdownPreviewTest.tsx
@@ -3,7 +3,13 @@
  */
 
 import { Assertor } from "./Assert"
-import { awaitEditorMode, getTemporaryFilePath, insertText, navigateToFile } from "./Common"
+import {
+    awaitEditorMode,
+    getElementByClassName,
+    getTemporaryFilePath,
+    insertText,
+    navigateToFile,
+} from "./Common"
 
 import * as Oni from "oni-api"
 
@@ -11,6 +17,7 @@ interface IMarkdownPreviewPlugin {
     isPaneOpen(): boolean
     getUnrenderedContent(): string
     getRenderedContent(): string
+    toggle(): void
 }
 
 export const settings = {
@@ -24,25 +31,91 @@ export async function test(oni: Oni.Plugin.Api) {
 
     await oni.automation.waitForEditors()
 
+    // Wait for Plugin to be loaded
     await oni.automation.waitFor(() => oni.plugins.loaded)
     const markdownPlugin = oni.plugins.getPlugin(
         "oni-plugin-markdown-preview",
     ) as IMarkdownPreviewPlugin
     assert.defined(markdownPlugin, "plugin instance")
 
-    assert.assert(!markdownPlugin.isPaneOpen(), "Preview pane is not initially closed")
+    // Check its not open by default
+    assert.assert(!markdownPlugin.isPaneOpen(), "Preview pane is initially closed.")
 
-    await navigateToFile(getTemporaryFilePath("md"), oni)
+    // Check it opens when navigating into a markdown file.
+    const markdownFilePath = getTemporaryFilePath("md")
+    await navigateToFile(markdownFilePath, oni)
     await oni.automation.waitFor(() => markdownPlugin.isPaneOpen())
+
     assert.isEmpty(
         markdownPlugin.getUnrenderedContent().trim(),
-        "Preview pane for empty Markdown buffer",
+        "Preview pane shown for Markdown buffer.",
     )
 
+    // Check a Title is rendered correctly.
     await insertText(oni, "# Title 1")
     assert.contains(
         markdownPlugin.getRenderedContent(),
         ">Title 1</h1>",
-        "Preview pane with rendered header element",
+        "Preview pane with renders header element.",
+    )
+
+    // Check syntax highlights are applied.
+    oni.automation.sendKeys("o")
+    await oni.automation.waitFor(() => oni.editors.activeEditor.mode === "insert")
+
+    oni.automation.sendKeys("```<enter>")
+    oni.automation.sendKeys("const test = 'Oni'<enter>")
+    oni.automation.sendKeys("```")
+    oni.automation.sendKeys("<esc>")
+
+    await oni.automation.waitFor(() => oni.editors.activeEditor.mode === "normal")
+
+    assert.contains(
+        markdownPlugin.getRenderedContent(),
+        "code>",
+        "Code block present in preview HTML.",
+    )
+
+    assert.assert(
+        getElementByClassName("hljs-keyword").innerText === "const",
+        "Syntax highlights present in preview HTML.",
+    )
+
+    // Finally, test swapping between files.
+    // Swapping to a non-MD file should close it.
+    // Swapping to an MD file should open it.
+    // Closing the MD preview manually should cause it to remain closed.
+
+    const nonMDFilePath = getTemporaryFilePath("ts")
+
+    await navigateToFile(nonMDFilePath, oni)
+    await oni.automation.waitFor(
+        () => oni.editors.activeEditor.activeBuffer.language === "typescript",
+    )
+    assert.assert(!markdownPlugin.isPaneOpen(), "Preview pane is closed for non-MD file.")
+
+    await navigateToFile(markdownFilePath, oni)
+    await oni.automation.waitFor(
+        () => oni.editors.activeEditor.activeBuffer.language === "markdown",
+    )
+    assert.assert(markdownPlugin.isPaneOpen(), "Preview pane opens for MD file.")
+
+    // Manually closing preview, should remain closed now.
+    markdownPlugin.toggle()
+    assert.assert(!markdownPlugin.isPaneOpen(), "Preview pane closes on toggle.")
+
+    await navigateToFile(nonMDFilePath, oni)
+    await oni.automation.waitFor(
+        () => oni.editors.activeEditor.activeBuffer.language === "typescript",
+    )
+    await navigateToFile(markdownFilePath, oni)
+    await oni.automation.waitFor(
+        () => oni.editors.activeEditor.activeBuffer.language === "markdown",
+    )
+
+    // Should remain closed when swapping back in.
+    assert.assert(
+        !markdownPlugin.isPaneOpen(),
+        "Preview pane remains closed for MD file when manually closed.",
     )
 }
diff --git a/yarn.lock b/yarn.lock
index 59e5499134..b67760ab78 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -110,6 +110,10 @@
     "@types/minimatch" "*"
     "@types/node" "*"
 
+"@types/highlight.js@^9.12.2":
+  version "9.12.3"
+  resolved "https://registry.yarnpkg.com/@types/highlight.js/-/highlight.js-9.12.3.tgz#b672cfaac25cbbc634a0fd92c515f66faa18dbca"
+
 "@types/jest@^22.1.3":
   version "22.1.3"
   resolved "https://registry.yarnpkg.com/@types/jest/-/jest-22.1.3.tgz#25da391935e6fac537551456f077ce03144ec168"
@@ -134,9 +138,9 @@
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/@types/lolex/-/lolex-2.1.0.tgz#7a53611a6c970574173a7d92ce9a0da000652725"
 
-"@types/marked@^0.3.0":
-  version "0.3.0"
-  resolved "https://registry.yarnpkg.com/@types/marked/-/marked-0.3.0.tgz#583c223dd33385a1dda01aaf77b0cd0411c4b524"
+"@types/marked@^0.4.0":
+  version "0.4.0"
+  resolved "https://registry.yarnpkg.com/@types/marked/-/marked-0.4.0.tgz#057a6165703e7419217f8ffc6887747f980b6315"
 
 "@types/minimatch@*":
   version "3.0.3"
@@ -4855,6 +4859,10 @@ he@1.1.1, he@1.1.x:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/he/-/he-1.1.1.tgz#93410fd21b009735151f8868c2f271f3427e23fd"
 
+highlight.js@^9.12.0:
+  version "9.12.0"
+  resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-9.12.0.tgz#e6d9dbe57cbefe60751f02af336195870c90c01e"
+
 hmac-drbg@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/hmac-drbg/-/hmac-drbg-1.0.1.tgz#d2745701025a6c775a6c545793ed502fc0c649a1"