diff --git a/src/lib/expandApplyAtRules.js b/src/lib/expandApplyAtRules.js
index fa87052..0c1be5f 100644
--- a/src/lib/expandApplyAtRules.js
+++ b/src/lib/expandApplyAtRules.js
@@ -27,7 +27,6 @@ function buildApplyCache(applyCandidates, context) {
   return context.applyClassCache
 }
 
-// TODO: Apply `!important` stuff correctly instead of just skipping it
 function extractApplyCandidates(params) {
   let candidates = params.split(/[\s\t\n]+/g)
 
diff --git a/src/lib/generateRules.js b/src/lib/generateRules.js
index e1d4950..ab013af 100644
--- a/src/lib/generateRules.js
+++ b/src/lib/generateRules.js
@@ -217,10 +217,19 @@ function generateRules(candidates, context) {
   }
 
   return allRules.flat(1).map(([{ sort, layer, options }, rule]) => {
-    if (context.tailwindConfig.important === true && options.respectImportant) {
-      rule.walkDecls((d) => {
-        d.important = true
-      })
+    if (options.respectImportant) {
+      if (context.tailwindConfig.important === true && options.respectImportant) {
+        rule.walkDecls((d) => {
+          d.important = true
+        })
+      } else if (typeof context.tailwindConfig.important === 'string') {
+        if (rule.type === 'rule') {
+          rule.selectors = rule.selectors.map((s) => `${context.tailwindConfig.important} ${s}`)
+        }
+        rule.walkRules((r) => {
+          r.selectors = r.selectors.map((s) => `${context.tailwindConfig.important} ${s}`)
+        })
+      }
     }
     return [sort | context.layerOrder[layer], rule]
   })
diff --git a/tests/04-important-selector.test.css b/tests/04-important-selector.test.css
new file mode 100644
index 0000000..122f0b2
--- /dev/null
+++ b/tests/04-important-selector.test.css
@@ -0,0 +1,71 @@
+* {
+  --tw-shadow: 0 0 #0000;
+  --tw-ring-inset: var(--tw-empty, /*!*/ /*!*/);
+  --tw-ring-offset-width: 0px;
+  --tw-ring-offset-color: #fff;
+  --tw-ring-color: rgba(59, 130, 246, 0.5);
+  --tw-ring-offset-shadow: 0 0 #0000;
+  --tw-ring-shadow: 0 0 #0000;
+}
+.container {
+  width: 100%;
+}
+@media (min-width: 640px) {
+  .container {
+    max-width: 640px;
+  }
+}
+@media (min-width: 768px) {
+  .container {
+    max-width: 768px;
+  }
+}
+@media (min-width: 1024px) {
+  .container {
+    max-width: 1024px;
+  }
+}
+@media (min-width: 1280px) {
+  .container {
+    max-width: 1280px;
+  }
+}
+@media (min-width: 1536px) {
+  .container {
+    max-width: 1536px;
+  }
+}
+#app .btn {
+  button: yes;
+}
+.custom-component {
+  font-weight: 700;
+}
+#app .custom-important-component {
+  text-align: center;
+}
+#app .font-bold {
+  font-weight: 700;
+}
+.custom-util {
+  button: no;
+}
+#app .group:hover .group-hover\:focus-within\:text-left:focus-within {
+  text-align: left;
+}
+#app [dir='rtl'] .rtl\:active\:text-center:active {
+  text-align: center;
+}
+@media (prefers-reduced-motion: no-preference) {
+  #app .motion-safe\:hover\:text-center:hover {
+    text-align: center;
+  }
+}
+#app .dark .dark\:focus\:text-left:focus {
+  text-align: left;
+}
+@media (min-width: 768px) {
+  #app .md\:hover\:text-right:hover {
+    text-align: right;
+  }
+}
diff --git a/tests/04-important-selector.test.html b/tests/04-important-selector.test.html
new file mode 100644
index 0000000..5dfa917
--- /dev/null
+++ b/tests/04-important-selector.test.html
@@ -0,0 +1,11 @@
+<div class="container"></div>
+<div class="btn"></div>
+<div class="custom-util"></div>
+<div class="custom-component"></div>
+<div class="custom-important-component"></div>
+<div class="font-bold"></div>
+<div class="md:hover:text-right"></div>
+<div class="motion-safe:hover:text-center"></div>
+<div class="dark:focus:text-left"></div>
+<div class="group-hover:focus-within:text-left"></div>
+<div class="rtl:active:text-center"></div>
diff --git a/tests/04-important-selector.test.js b/tests/04-important-selector.test.js
new file mode 100644
index 0000000..a36291c
--- /dev/null
+++ b/tests/04-important-selector.test.js
@@ -0,0 +1,59 @@
+const postcss = require('postcss')
+const tailwind = require('../src/index.js')
+const fs = require('fs')
+const path = require('path')
+
+function run(input, config = {}) {
+  return postcss([tailwind(config)]).process(input, { from: path.resolve(__filename) })
+}
+
+test('important boolean', () => {
+  let config = {
+    important: '#app',
+    darkMode: 'class',
+    purge: [path.resolve(__dirname, './04-important-selector.test.html')],
+    corePlugins: { preflight: false },
+    theme: {},
+    plugins: [
+      function ({ addComponents, addUtilities }) {
+        addComponents(
+          {
+            '.btn': {
+              button: 'yes',
+            },
+          },
+          { respectImportant: true }
+        )
+        addUtilities(
+          {
+            '.custom-util': {
+              button: 'no',
+            },
+          },
+          { respectImportant: false }
+        )
+      },
+    ],
+  }
+
+  let css = `
+    @tailwind base;
+    @tailwind components;
+    @layer components {
+      .custom-component {
+        @apply font-bold;
+      }
+      .custom-important-component {
+        @apply text-center !important;
+      }
+    }
+    @tailwind utilities;
+  `
+
+  return run(css, config).then((result) => {
+    let expectedPath = path.resolve(__dirname, './04-important-selector.test.css')
+    let expected = fs.readFileSync(expectedPath, 'utf8')
+
+    expect(result.css).toMatchCss(expected)
+  })
+})