diff --git a/src/data/input_datetime.ts b/src/data/input_datetime.ts
index 16a2f1b09d..08af492afd 100644
--- a/src/data/input_datetime.ts
+++ b/src/data/input_datetime.ts
@@ -1,3 +1,4 @@
+import { HassEntity } from "home-assistant-js-websocket";
 import { HomeAssistant } from "../types";
 
 export interface InputDateTime {
@@ -17,6 +18,19 @@ export interface InputDateTimeMutableParams {
   has_date: boolean;
 }
 
+export const stateToIsoDateString = (entityState: HassEntity) =>
+  `${entityState.attributes.year || "1970"}-${String(
+    entityState.attributes.month || "01"
+  ).padStart(2, "0")}-${String(entityState.attributes.day || "01").padStart(
+    2,
+    "0"
+  )}T${String(entityState.attributes.hour || "00").padStart(2, "0")}:${String(
+    entityState.attributes.minute || "00"
+  ).padStart(2, "0")}:${String(entityState.attributes.second || "00").padStart(
+    2,
+    "0"
+  )}`;
+
 export const setInputDateTimeValue = (
   hass: HomeAssistant,
   entityId: string,
diff --git a/src/dialogs/more-info/controls/more-info-input_datetime.ts b/src/dialogs/more-info/controls/more-info-input_datetime.ts
index a0f11eb726..2bcb5f534e 100644
--- a/src/dialogs/more-info/controls/more-info-input_datetime.ts
+++ b/src/dialogs/more-info/controls/more-info-input_datetime.ts
@@ -4,7 +4,10 @@ import { customElement, property } from "lit/decorators";
 import "../../../components/ha-date-input";
 import "../../../components/ha-time-input";
 import { UNAVAILABLE_STATES, UNKNOWN } from "../../../data/entity";
-import { setInputDateTimeValue } from "../../../data/input_datetime";
+import {
+  setInputDateTimeValue,
+  stateToIsoDateString,
+} from "../../../data/input_datetime";
 import type { HomeAssistant } from "../../../types";
 
 @customElement("more-info-input_datetime")
@@ -24,7 +27,7 @@ class MoreInfoInputDatetime extends LitElement {
             ? html`
                 <ha-date-input
                   .locale=${this.hass.locale}
-                  .value=${`${this.stateObj.attributes.year}-${this.stateObj.attributes.month}-${this.stateObj.attributes.day}`}
+                  .value=${stateToIsoDateString(this.stateObj)}
                   .disabled=${UNAVAILABLE_STATES.includes(this.stateObj.state)}
                   @value-changed=${this._dateChanged}
                 >
diff --git a/src/panels/lovelace/entity-rows/hui-input-datetime-entity-row.ts b/src/panels/lovelace/entity-rows/hui-input-datetime-entity-row.ts
index 393f0bc7b1..f542b2ec6d 100644
--- a/src/panels/lovelace/entity-rows/hui-input-datetime-entity-row.ts
+++ b/src/panels/lovelace/entity-rows/hui-input-datetime-entity-row.ts
@@ -9,7 +9,10 @@ import {
 import { customElement, property, state } from "lit/decorators";
 import "../../../components/ha-date-input";
 import { UNAVAILABLE_STATES, UNKNOWN } from "../../../data/entity";
-import { setInputDateTimeValue } from "../../../data/input_datetime";
+import {
+  setInputDateTimeValue,
+  stateToIsoDateString,
+} from "../../../data/input_datetime";
 import type { HomeAssistant } from "../../../types";
 import { hasConfigOrEntityChanged } from "../common/has-changed";
 import "../components/hui-generic-entity-row";
@@ -65,7 +68,7 @@ class HuiInputDatetimeEntityRow extends LitElement implements LovelaceRow {
                 .label=${stateObj.attributes.has_time ? name : undefined}
                 .locale=${this.hass.locale}
                 .disabled=${UNAVAILABLE_STATES.includes(stateObj.state)}
-                .value=${`${stateObj.attributes.year}-${stateObj.attributes.month}-${stateObj.attributes.day}`}
+                .value=${stateToIsoDateString(stateObj)}
                 @value-changed=${this._dateChanged}
               >
               </ha-date-input>