diff --git a/lib/rules/multiline-comment-style.js b/lib/rules/multiline-comment-style.js
index fb50e1522ea..9524818b8bd 100644
--- a/lib/rules/multiline-comment-style.js
+++ b/lib/rules/multiline-comment-style.js
@@ -316,6 +316,10 @@ module.exports = {
                                         const [, prefix = "", initialOffset = ""] = lineTextToAlignWith.match(/^(\s*(?:\/?\*)?(\s*))/u) || [];
 
                                         offset = `${commentTextPrefix.slice(prefix.length)}${initialOffset}`;
+
+                                        if (/^\s*\//u.test(lineText) && offset.length === 0) {
+                                            offset += " ";
+                                        }
                                         break;
                                     }
 
diff --git a/tests/lib/rules/multiline-comment-style.js b/tests/lib/rules/multiline-comment-style.js
index c69265ba9e2..456494b7bd5 100644
--- a/tests/lib/rules/multiline-comment-style.js
+++ b/tests/lib/rules/multiline-comment-style.js
@@ -328,6 +328,15 @@ ruleTester.run("multiline-comment-style", rule, {
                  */
             `,
             options: ["separate-lines"]
+        },
+        {
+            code: `
+                /*
+                 * // a line comment
+                 *some.code();
+                 */
+            `,
+            options: ["starred-block"]
         }
     ],
 
@@ -1379,6 +1388,91 @@ ${"                   "}
                 { messageId: "missingStar", line: 4 },
                 { messageId: "endNewline", line: 4 }
             ]
+        },
+        {
+            code: `
+                /*
+                 // a line comment
+                 some.code();
+                 */
+            `,
+            output: `
+                /*
+                 * // a line comment
+                 *some.code();
+                 */
+            `,
+            options: ["starred-block"],
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 }
+            ]
+        },
+        {
+            code: `
+                /*
+                 // a line comment
+                 * some.code();
+                 */
+            `,
+            output: `
+                /*
+                 * // a line comment
+                 * some.code();
+                 */
+            `,
+            options: ["starred-block"],
+            errors: [
+                { messageId: "missingStar", line: 3 }
+            ]
+        },
+        {
+            code: `
+                ////This comment is in
+                //\`separate-lines\` format.
+            `,
+            output: null,
+            options: ["starred-block"],
+            errors: [
+                { messageId: "expectedBlock", line: 2 }
+            ]
+        },
+        {
+            code: `
+                // // This comment is in
+                // \`separate-lines\` format.
+            `,
+            output: null,
+            options: ["starred-block"],
+            errors: [
+                { messageId: "expectedBlock", line: 2 }
+            ]
+        },
+        {
+            code: `
+                /*
+                {
+                \t"foo": 1,
+                \t//"bar": 2
+                }
+                */
+            `,
+            output: `
+                /*
+                 *{
+                 *\t"foo": 1,
+                 *\t//"bar": 2
+                 *}
+                 */
+            `,
+            options: ["starred-block"],
+            errors: [
+                { messageId: "missingStar", line: 3 },
+                { messageId: "missingStar", line: 4 },
+                { messageId: "missingStar", line: 5 },
+                { messageId: "missingStar", line: 6 },
+                { messageId: "alignment", line: 7 }
+            ]
         }
     ]
 });