diff --git a/addons/web/static/src/core/datepicker/datepicker.js b/addons/web/static/src/core/datepicker/datepicker.js
index 82d96f5c615..bc221c5f535 100644
--- a/addons/web/static/src/core/datepicker/datepicker.js
+++ b/addons/web/static/src/core/datepicker/datepicker.js
@@ -146,13 +146,13 @@ export class DatePicker extends Component {
         if (typeof commandOrParams === "object") {
             const format = luxonFormatToMomentFormat(this.props.format || this.defaultFormat);
             const params = { ...commandOrParams, format };
+            if (!params.locale && commandOrParams.date) {
+                params.locale = commandOrParams.date.locale;
+            }
             for (const prop in params) {
                 if (params[prop] instanceof DateTime) {
                     const luxonDate = params[prop];
                     const momentDate = luxonDateToMomentDate(luxonDate);
-                    if (momentDate.locale() !== luxonDate.locale) {
-                        momentDate.locale(params.locale);
-                    }
                     params[prop] = momentDate;
                 }
             }
diff --git a/addons/web/static/src/core/l10n/localization_service.js b/addons/web/static/src/core/l10n/localization_service.js
index c24d20abbe9..a240dcf4793 100644
--- a/addons/web/static/src/core/l10n/localization_service.js
+++ b/addons/web/static/src/core/l10n/localization_service.js
@@ -41,6 +41,16 @@ export const localizationService = {
         Object.setPrototypeOf(translatedTerms, terms);
         env._t = _t;
         env.qweb.translateFn = _t;
+
+        // Setup lang inside luxon. The locale codes received from the server contain "_", whereas
+        // the Intl codes use "-" (Unicode BCP 47). There's only one exception, which is locale
+        // "sr@latin", for which we manually fallback to the "sr-Latn-RS" locale.
+        if (lang === "sr@latin") {
+            luxon.Settings.defaultLocale = "sr-Latn-RS";
+        } else if (lang) {
+            luxon.Settings.defaultLocale = lang.replace(/_/g, "-");
+        }
+
         const dateFormat = strftimeToLuxonFormat(userLocalization.date_format);
         const timeFormat = strftimeToLuxonFormat(userLocalization.time_format);
         const dateTimeFormat = `${dateFormat} ${timeFormat}`;
diff --git a/addons/web/static/tests/core/datepicker_tests.js b/addons/web/static/tests/core/datepicker_tests.js
index f0da030c8b7..6b9f7359832 100644
--- a/addons/web/static/tests/core/datepicker_tests.js
+++ b/addons/web/static/tests/core/datepicker_tests.js
@@ -127,7 +127,7 @@ QUnit.module("Components", () => {
         assert.verifySteps(["datetime-changed"]);
     });
 
-    QUnit.test("pick a date with locale", async function (assert) {
+    QUnit.test("pick a date with locale (locale given in props)", async function (assert) {
         assert.expect(5);
 
         const picker = await mountPicker(DatePicker, {
@@ -158,6 +158,39 @@ QUnit.module("Components", () => {
         assert.verifySteps(["datetime-changed"]);
     });
 
+    QUnit.test("pick a date with locale (locale from date props)", async function (assert) {
+        assert.expect(5);
+
+        const picker = await mountPicker(DatePicker, {
+            props: {
+                date: DateTime.fromFormat("09/01/1997", "dd/MM/yyyy", {
+                    zone: "utc",
+                    locale: useFRLocale(),
+                }),
+                format: "dd MMM, yyyy",
+            },
+            onDateChange: (ev) => {
+                assert.step("datetime-changed");
+                assert.strictEqual(
+                    ev.detail.date.toFormat("dd/MM/yyyy"),
+                    "01/09/1997",
+                    "Event should transmit the correct date"
+                );
+            },
+        });
+        const input = picker.el.querySelector(".o_datepicker_input");
+
+        assert.strictEqual(input.value, "09 janv., 1997");
+
+        await click(input);
+        await click(document.querySelector(".datepicker .picker-switch")); // month picker
+        await click(document.querySelectorAll(".datepicker .month")[8]); // september
+        await click(document.querySelector(".datepicker .day")); // first day
+
+        assert.strictEqual(input.value, "01 sept., 1997");
+        assert.verifySteps(["datetime-changed"]);
+    });
+
     QUnit.test("enter a date value", async function (assert) {
         assert.expect(5);
 
diff --git a/addons/web/static/tests/core/l10n/translation_tests.js b/addons/web/static/tests/core/l10n/translation_tests.js
index ded6e1df950..3bfe6d1848e 100644
--- a/addons/web/static/tests/core/l10n/translation_tests.js
+++ b/addons/web/static/tests/core/l10n/translation_tests.js
@@ -1,11 +1,15 @@
 /** @odoo-module **/
 
+import { browser } from "@web/core/browser/browser";
 import { translatedTerms, _lt } from "@web/core/l10n/translation";
+import { localizationService } from "@web/core/l10n/localization_service";
 import { registry } from "@web/core/registry";
 import { patch, unpatch } from "@web/core/utils/patch";
-import { makeTestEnv } from "../../helpers/mock_env";
-import { makeFakeLocalizationService } from "../../helpers/mock_services";
-import { getFixture } from "../../helpers/utils";
+import { session } from "@web/session";
+import { makeTestEnv } from "@web/../tests/helpers/mock_env";
+import { makeFakeLocalizationService } from "@web/../tests/helpers/mock_services";
+import { getFixture, patchWithCleanup } from "@web/../tests/helpers/utils";
+import { registerCleanup } from "@web/../tests/helpers/cleanup";
 
 const { mount } = owl;
 
@@ -55,3 +59,39 @@ QUnit.test("_t is in env", async (assert) => {
     assert.strictEqual(target.innerText, "Bonjour");
     unpatch(translatedTerms, "add translations");
 });
+
+QUnit.test("luxon is configured in the correct lang", async (assert) => {
+    const defaultLocale = luxon.Settings.defaultLocale;
+    registerCleanup(() => {
+        luxon.Settings.defaultLocale = defaultLocale;
+    });
+    patchWithCleanup(session, {
+        user_context: {...session.user_context, lang: "fr_BE"},
+    });
+    patchWithCleanup(browser, {
+        fetch() {
+            return {
+                ok: true,
+                json() {
+                    return {
+                        modules: {},
+                        lang_parameters: {
+                            direction: "ltr",
+                            date_format: "%d/%m/%Y",
+                            time_format: "%H:%M:%S",
+                            grouping: "[3,0]",
+                            decimal_point: ",",
+                            thousands_sep: ".",
+                            week_start: 1,
+                        },
+                    };
+                },
+            };
+        },
+    });
+    serviceRegistry.add("localization", localizationService);
+
+    await makeTestEnv();
+
+    assert.strictEqual(luxon.DateTime.utc(2021, 12, 10).toFormat("MMMM"), "décembre");
+});