diff --git a/devtools/client/webconsole/components/Output/message-types/ConsoleCommand.js b/devtools/client/webconsole/components/Output/message-types/ConsoleCommand.js
index 5132f34b9ade..dbb482faba30 100644
--- a/devtools/client/webconsole/components/Output/message-types/ConsoleCommand.js
+++ b/devtools/client/webconsole/components/Output/message-types/ConsoleCommand.js
@@ -36,11 +36,13 @@ function ConsoleCommand(props) {
     maybeScrollToBottom,
   } = props;
 
-  const { indent, source, type, level, messageText, timeStamp } = message;
+  const { indent, source, type, level, timeStamp } = message;
+  const messageText = trimCode(message.messageText);
 
   // This uses a Custom Element to syntax highlight when possible. If it's not
   // (no CodeMirror editor), then it will just render text.
   const messageBody = createElement("syntax-highlighted", null, messageText);
+
   return Message({
     source,
     type,
@@ -57,3 +59,21 @@ function ConsoleCommand(props) {
 }
 
 module.exports = ConsoleCommand;
+
+/**
+ * Trim user input to avoid blank lines before and after messages
+ */
+function trimCode(input) {
+  if (typeof input !== "string") {
+    return input;
+  }
+
+  // Trim on both edges if we have a single line of content
+  if (input.trim().includes("\n") === false) {
+    return input.trim();
+  }
+
+  // For multiline input we want to keep the indentation of the first line
+  // with non-whitespace, so we can't .trim()/.trimStart().
+  return input.replace(/^\s*\n/, "").trimEnd();
+}
diff --git a/devtools/client/webconsole/test/mochitest/browser.ini b/devtools/client/webconsole/test/mochitest/browser.ini
index fa50e8bf4a4d..e6e5ee140f33 100644
--- a/devtools/client/webconsole/test/mochitest/browser.ini
+++ b/devtools/client/webconsole/test/mochitest/browser.ini
@@ -413,6 +413,7 @@ tags = clipboard
 [browser_webconsole_output_copy_newlines.js]
 tags = clipboard
 [browser_webconsole_output_order.js]
+[browser_webconsole_output_trimmed.js]
 [browser_webconsole_persist.js]
 [browser_webconsole_primitive_stacktrace.js]
 [browser_webconsole_promise_rejected_object.js]
diff --git a/devtools/client/webconsole/test/mochitest/browser_webconsole_output_trimmed.js b/devtools/client/webconsole/test/mochitest/browser_webconsole_output_trimmed.js
new file mode 100644
index 000000000000..7e7cd8ff6e0c
--- /dev/null
+++ b/devtools/client/webconsole/test/mochitest/browser_webconsole_output_trimmed.js
@@ -0,0 +1,102 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Tests that we trim start and end whitespace in user input
+// in the messages list
+
+"use strict";
+
+const TEST_URI = `http://example.com/browser/devtools/client/webconsole/test/mochitest/test-console.html`;
+
+const TEST_ITEMS = [
+  {
+    name: "Commands without whitespace are not affected by trimming",
+    command: "Math.PI==='3.14159'",
+    expected: "Math.PI==='3.14159'",
+  },
+  {
+    name: "Trims whitespace before and after a command (single line case)",
+    command: "\t\t    (window.o_O || {})   ['  O_o  ']    ",
+    expected: "(window.o_O || {})   ['  O_o  ']",
+  },
+  {
+    name:
+      "When trimming a whitespace before and after a command, " +
+      "it keeps indentation for each contentful line",
+    command: "  \n  \n  1,\n  2,\n  3\n  \n  ",
+    expected: "  1,\n  2,\n  3",
+  },
+  {
+    name:
+      "When trimming a whitespace before and after a command, " +
+      "it keeps trailing whitespace for all lines except the last",
+    command:
+      "\n" +
+      "    let numbers = [1,\n" +
+      "                   2,  \n" +
+      "                   3];\n" +
+      "    \n" +
+      "    \n" +
+      "    function addNumber() {        \n" +
+      "      numbers.push(numbers.length + 1);\n" +
+      "    }    \n" +
+      "    ",
+    expected:
+      "    let numbers = [1,\n" +
+      "                   2,  \n" +
+      "                   3];\n" +
+      "    \n" +
+      "    \n" +
+      "    function addNumber() {        \n" +
+      "      numbers.push(numbers.length + 1);\n" +
+      "    }",
+  },
+];
+
+add_task(async function() {
+  const hud = await openNewTabAndConsole(TEST_URI);
+
+  // Check that expected output and actual trimmed output match
+  for (const { name, command, expected } of TEST_ITEMS) {
+    hud.ui.clearOutput();
+    await hud.jsterm.execute(command);
+
+    const result = await waitFor(() => getDisplayedInput(hud));
+
+    if (result === expected) {
+      ok(true, name);
+    } else {
+      ok(false, formatError(name, result, expected));
+    }
+  }
+});
+
+/**
+ * Get the text content of the latest command logged in the console
+ * @param {WebConsole} hud: The webconsole
+ * @return {string|null}
+ */
+function getDisplayedInput(hud) {
+  const message = Array.from(
+    hud.ui.outputNode.querySelectorAll(".message.command")
+  ).pop();
+
+  if (message) {
+    return message.querySelector("syntax-highlighted").textContent;
+  }
+
+  return null;
+}
+
+/**
+ * Format a "Got vs Expected" error message on multiple lines,
+ * making whitespace more visible in console output.
+ */
+function formatError(name, result, expected) {
+  const quote = str =>
+    typeof str === "string"
+      ? "> " + str.replace(/ /g, "\u{B7}").replace(/\n/g, "\n> ")
+      : str;
+
+  return `${name}\nGot:\n${quote(result)}\nExpected:\n${quote(expected)}\n`;
+}