diff --git a/.changeset/rude-hornets-begin.md b/.changeset/rude-hornets-begin.md
new file mode 100644
index 0000000000..d1aaf43d77
--- /dev/null
+++ b/.changeset/rude-hornets-begin.md
@@ -0,0 +1,5 @@
+---
+"stylelint": patch
+---
+
+Fixed: `declaration-block-no-duplicate-properties` autofix for `!important`
diff --git a/lib/rules/declaration-block-no-duplicate-properties/__tests__/index.js b/lib/rules/declaration-block-no-duplicate-properties/__tests__/index.js
index 9049919421..d0fe44bb57 100644
--- a/lib/rules/declaration-block-no-duplicate-properties/__tests__/index.js
+++ b/lib/rules/declaration-block-no-duplicate-properties/__tests__/index.js
@@ -187,6 +187,24 @@ testRule({
 			endLine: 1,
 			endColumn: 55,
 		},
+		{
+			code: 'a { color: red !important; color: blue; }',
+			fixed: 'a { color: red !important; }',
+			message: messages.rejected('color'),
+			line: 1,
+			column: 28,
+			endLine: 1,
+			endColumn: 33,
+		},
+		{
+			code: 'a { color: red !important; color: blue !important; }',
+			fixed: 'a { color: blue !important; }',
+			message: messages.rejected('color'),
+			line: 1,
+			column: 28,
+			endLine: 1,
+			endColumn: 33,
+		},
 	],
 });
 
@@ -231,6 +249,11 @@ testRule({
 			fixed: 'p { display: inline-block; font-weight: 400; font-size: 1rem; color: red; }',
 			message: messages.rejected('font-size'),
 		},
+		{
+			code: 'p { font-size: 16px !important; font-weight: 400; font-size: 1rem; }',
+			fixed: 'p { font-size: 16px !important; font-weight: 400; }',
+			message: messages.rejected('font-size'),
+		},
 	],
 });
 
@@ -252,6 +275,16 @@ testRule({
 			fixed: 'p { font-size: 16px; font-weight: 400; }',
 			message: messages.rejected('font-size'),
 		},
+		{
+			code: 'p { font-size: 16px !important; font-weight: 400; font-size: 1rem; }',
+			fixed: 'p { font-size: 16px !important; font-weight: 400; }',
+			message: messages.rejected('font-size'),
+		},
+		{
+			code: 'p { font-size: 16px; font-size: 16px !important; font-weight: 400; }',
+			fixed: 'p { font-size: 16px !important; font-weight: 400; }',
+			message: messages.rejected('font-size'),
+		},
 	],
 });
 
@@ -291,6 +324,16 @@ testRule({
 			fixed: 'p { width: -moz-fit-content; }',
 			message: messages.rejected('width'),
 		},
+		{
+			code: 'p { width: -moz-fit-content; width: -moz-fit-content !important; }',
+			fixed: 'p { width: -moz-fit-content !important; }',
+			message: messages.rejected('width'),
+		},
+		{
+			code: 'p { width: 100% !important; width: -moz-fit-content; }',
+			fixed: 'p { width: 100% !important; }',
+			message: messages.rejected('width'),
+		},
 	],
 });
 
@@ -309,6 +352,9 @@ testRule({
 		{
 			code: 'p { color: pink; background: orange; color: orange }',
 		},
+		{
+			code: 'p { color: pink; color: orange !important; }',
+		},
 	],
 
 	reject: [
@@ -322,6 +368,11 @@ testRule({
 			fixed: 'p { color: pink; background: white; }',
 			message: messages.rejected('background'),
 		},
+		{
+			code: 'p { background: orange; color: pink; background: white !important; }',
+			fixed: 'p { color: pink; background: white !important; }',
+			message: messages.rejected('background'),
+		},
 	],
 });
 
diff --git a/lib/rules/declaration-block-no-duplicate-properties/index.js b/lib/rules/declaration-block-no-duplicate-properties/index.js
index d81addb5ab..31a70524e0 100644
--- a/lib/rules/declaration-block-no-duplicate-properties/index.js
+++ b/lib/rules/declaration-block-no-duplicate-properties/index.js
@@ -66,6 +66,7 @@ const rule = (primary, secondaryOptions, context) => {
 				const prop = decl.prop;
 				const lowerProp = decl.prop.toLowerCase();
 				const value = decl.value;
+				const important = decl.important;
 
 				if (!isStandardSyntaxProperty(prop)) {
 					return;
@@ -88,11 +89,19 @@ const rule = (primary, secondaryOptions, context) => {
 				const indexDuplicate = decls.findIndex((d) => d.prop.toLowerCase() === lowerProp);
 
 				if (indexDuplicate !== -1) {
+					const duplicateDecl = decls[indexDuplicate];
+					const duplicateValue = duplicateDecl ? duplicateDecl.value : '';
+					const duplicateImportant = duplicateDecl ? duplicateDecl.important : false;
+
 					if (ignoreDiffValues || ignorePrefixlessSameValues) {
 						// fails if duplicates are not consecutive
 						if (indexDuplicate !== decls.length - 1) {
 							if (context.fix) {
-								removePreviousDuplicate(decls, lowerProp);
+								if (!important && duplicateImportant) {
+									decl.remove();
+								} else {
+									removePreviousDuplicate(decls, lowerProp);
+								}
 
 								return;
 							}
@@ -108,14 +117,15 @@ const rule = (primary, secondaryOptions, context) => {
 							return;
 						}
 
-						const duplicateDecl = decls[indexDuplicate];
-						const duplicateValue = duplicateDecl ? duplicateDecl.value : '';
-
 						if (ignorePrefixlessSameValues) {
 							// fails if values of consecutive, unprefixed duplicates are equal
 							if (vendor.unprefixed(value) !== vendor.unprefixed(duplicateValue)) {
 								if (context.fix) {
-									removePreviousDuplicate(decls, lowerProp);
+									if (!important && duplicateImportant) {
+										decl.remove();
+									} else {
+										removePreviousDuplicate(decls, lowerProp);
+									}
 
 									return;
 								}
@@ -159,7 +169,11 @@ const rule = (primary, secondaryOptions, context) => {
 					}
 
 					if (context.fix) {
-						removePreviousDuplicate(decls, lowerProp);
+						if (!important && duplicateImportant) {
+							decl.remove();
+						} else {
+							removePreviousDuplicate(decls, lowerProp);
+						}
 
 						return;
 					}