diff --git a/core/src/components/datetime/datetime-interface.ts b/core/src/components/datetime/datetime-interface.ts
index 2919e0c69d..c126b8d728 100644
--- a/core/src/components/datetime/datetime-interface.ts
+++ b/core/src/components/datetime/datetime-interface.ts
@@ -22,15 +22,15 @@ export type DatetimePresentation = 'date-time' | 'time-date' | 'date' | 'time' |
 
 export type TitleSelectedDatesFormatter = (selectedDates: string[]) => string;
 
-export type DatetimeHighlightStyle =
-  | {
-      textColor: string;
-      backgroundColor?: string;
-    }
-  | {
-      textColor?: string;
-      backgroundColor: string;
-    };
+/**
+ * DatetimeHighlightStyle must include textColor, backgroundColor, or border.
+ * It cannot be an empty object.
+ */
+export type DatetimeHighlightStyle = {
+  textColor?: string;
+  backgroundColor?: string;
+  border?: string;
+} & ({ textColor: string } | { backgroundColor: string } | { border: string });
 
 export type DatetimeHighlight = { date: string } & DatetimeHighlightStyle;
 
diff --git a/core/src/components/datetime/datetime.tsx b/core/src/components/datetime/datetime.tsx
index 1ede831377..2e3e111e56 100644
--- a/core/src/components/datetime/datetime.tsx
+++ b/core/src/components/datetime/datetime.tsx
@@ -2335,6 +2335,7 @@ export class Datetime implements ComponentInterface {
                         `${dateStyle ? dateStyle.backgroundColor : ''}`,
                         'important'
                       );
+                      el.style.setProperty('border', `${dateStyle ? dateStyle.border : ''}`, 'important');
                     }
                   }}
                   tabindex="-1"
diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts
index 8b3340e168..12f014b74e 100644
--- a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts
+++ b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts
@@ -21,16 +21,19 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
             date: '2023-01-01', // ensure selected date style overrides highlight
             textColor: '#800080',
             backgroundColor: '#ffc0cb',
+            border: '2px solid purple',
           },
           {
             date: '2023-01-02',
             textColor: '#b22222',
             backgroundColor: '#fa8072',
+            border: '2px solid purple',
           },
           {
             date: '2023-01-03',
             textColor: '#0000ff',
             backgroundColor: '#add8e6',
+            border: '2px solid purple',
           },
         ];
       });
@@ -52,6 +55,7 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
             return {
               textColor: '#b22222',
               backgroundColor: '#fa8072',
+              border: '2px solid purple',
             };
           }
 
@@ -59,6 +63,7 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
             return {
               textColor: '#800080',
               backgroundColor: '#ffc0cb',
+              border: '2px solid purple',
             };
           }
 
@@ -66,6 +71,7 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
             return {
               textColor: '#0000ff',
               backgroundColor: '#add8e6',
+              border: '2px solid purple',
             };
           }
 
@@ -77,7 +83,7 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
       await expect(datetime).toHaveScreenshot(screenshot(`datetime-highlightedDates-callback`));
     });
 
-    test('should render highlights correctly when only using one color or the other', async ({ page }) => {
+    test('should render highlights correctly when only using only one color property', async ({ page }) => {
       const datetime = page.locator('ion-datetime');
 
       await datetime.evaluate((el: HTMLIonDatetimeElement) => {
@@ -90,6 +96,10 @@ configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
             date: '2023-01-03',
             textColor: '#0000ff',
           },
+          {
+            date: '2023-01-04',
+            border: '2px solid purple',
+          },
         ];
       });
 
diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Chrome-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Chrome-linux.png
index 5f0f964db7..4cc405bd53 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Firefox-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Firefox-linux.png
index 5982c8888d..cc1c5ca41c 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Safari-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-ios-ltr-Mobile-Safari-linux.png
index f1081db356..fa99291a33 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-md-ltr-Mobile-Chrome-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-md-ltr-Mobile-Chrome-linux.png
index 3951614b6f..1501aab348 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-md-ltr-Mobile-Firefox-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-array-md-ltr-Mobile-Firefox-linux.png
index fca0edc6fa..357ee30381 100644
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index e2fb1c1242..5d5c5407b8 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-callback-ios-ltr-Mobile-Chrome-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-callback-ios-ltr-Mobile-Chrome-linux.png
index a129ea9b2b..6d76797731 100644
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index 92943d8a68..8628e1cd64 100644
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index 9a297d09c0..6e48031446 100644
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index 25d5e2cb67..820c0049c3 100644
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index 9c0ccbdeb9..cb0e0b8afe 100644
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index cab41c014c..6b77ebb986 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-ios-ltr-Mobile-Chrome-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-ios-ltr-Mobile-Chrome-linux.png
index cfbc03d994..74b305490f 100644
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index 84b899ad9c..1e689d045a 100644
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index 575cc016db..4b645645d2 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Chrome-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Chrome-linux.png
index f06a13cab0..3f1532259d 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Firefox-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Firefox-linux.png
index df39697321..86952a9a18 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Safari-linux.png b/core/src/components/datetime/test/highlighted-dates/datetime.e2e.ts-snapshots/datetime-highlightedDates-single-color-md-ltr-Mobile-Safari-linux.png
index 45aa687133..f70b8daadb 100644
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diff --git a/core/src/components/datetime/test/highlighted-dates/index.html b/core/src/components/datetime/test/highlighted-dates/index.html
index 965865b7b0..f523afad5b 100644
--- a/core/src/components/datetime/test/highlighted-dates/index.html
+++ b/core/src/components/datetime/test/highlighted-dates/index.html
@@ -78,6 +78,10 @@
           textColor: 'blue',
           backgroundColor: 'lightblue',
         },
+        {
+          date: '2023-01-07',
+          border: '2px dotted red',
+        },
       ];
 
       document.querySelector('#withCallback').highlightedDates = (isoString) => {
@@ -103,6 +107,7 @@
           date: new Date().toISOString().split('T')[0],
           textColor: 'purple',
           backgroundColor: 'pink',
+          border: '2px solid purple',
         },
       ];
     </script>
diff --git a/core/src/components/datetime/utils/state.ts b/core/src/components/datetime/utils/state.ts
index 80abeb25f5..fc05b968b6 100644
--- a/core/src/components/datetime/utils/state.ts
+++ b/core/src/components/datetime/utils/state.ts
@@ -207,6 +207,7 @@ export const getHighlightStyles = (
       return {
         textColor: matchingHighlight.textColor,
         backgroundColor: matchingHighlight.backgroundColor,
+        border: matchingHighlight.border,
       } as DatetimeHighlightStyle;
     }
   } else {