diff --git a/packages/lib/CalendarService.ts b/packages/lib/CalendarService.ts
index d4c0f62049..b2f6676833 100644
--- a/packages/lib/CalendarService.ts
+++ b/packages/lib/CalendarService.ts
@@ -276,6 +276,38 @@ export default abstract class BaseCalendarService implements Calendar {
     }
   }
 
+  /**
+   * getUserTimezoneFromDB() retrieves the timezone of a user from the database.
+   *
+   * @param {number} id - The user's unique identifier.
+   * @returns {Promise<string | undefined>} - A Promise that resolves to the user's timezone or "Europe/London" as a default value if the timezone is not found.
+   */
+  getUserTimezoneFromDB = async (id: number): Promise<string | undefined> => {
+    const prisma = await import("@calcom/prisma").then((mod) => mod.default);
+    const user = await prisma.user.findUnique({
+      where: {
+        id,
+      },
+      select: {
+        timeZone: true,
+      },
+    });
+    return user?.timeZone;
+  };
+
+  /**
+   * getUserId() extracts the user ID from the first calendar in an array of IntegrationCalendars.
+   *
+   * @param {IntegrationCalendar[]} selectedCalendars - An array of IntegrationCalendars.
+   * @returns {number | null} - The user ID associated with the first calendar in the array, or null if the array is empty or the user ID is not found.
+   */
+  getUserId = (selectedCalendars: IntegrationCalendar[]): number | null => {
+    if (selectedCalendars.length === 0) {
+      return null;
+    }
+    return selectedCalendars[0].userId || null;
+  };
+
   isValidFormat = (url: string): boolean => {
     const allowedExtensions = ["eml", "ics"];
     const urlExtension = getFileExtension(url);
@@ -299,6 +331,10 @@ export default abstract class BaseCalendarService implements Calendar {
       dateTo,
       headers: this.headers,
     });
+
+    const userId = this.getUserId(selectedCalendars);
+    // we use the userId from selectedCalendars to fetch the user's timeZone from the database primarily for all-day events without any timezone information
+    const userTimeZone = userId ? await this.getUserTimezoneFromDB(userId) : "Europe/London";
     const events: { start: string; end: string }[] = [];
     objects.forEach((object) => {
       if (object.data == null || JSON.stringify(object.data) == "{}") return;
@@ -322,26 +358,31 @@ export default abstract class BaseCalendarService implements Calendar {
         const isUTC = timezone === "Z";
         const tzid: string | undefined = vevent?.getFirstPropertyValue("tzid") || isUTC ? "UTC" : timezone;
         // In case of icalendar, when only tzid is available without vtimezone, we need to add vtimezone explicitly to take care of timezone diff
-        if (!vcalendar.getFirstSubcomponent("vtimezone") && tzid) {
-          try {
-            const timezoneComp = new ICAL.Component("vtimezone");
-            timezoneComp.addPropertyWithValue("tzid", tzid);
-            const standard = new ICAL.Component("standard");
+        if (!vcalendar.getFirstSubcomponent("vtimezone")) {
+          const timezoneToUse = tzid || userTimeZone;
+          if (timezoneToUse) {
+            try {
+              const timezoneComp = new ICAL.Component("vtimezone");
+              timezoneComp.addPropertyWithValue("tzid", timezoneToUse);
+              const standard = new ICAL.Component("standard");
 
-            // get timezone offset
-            const tzoffsetfrom = dayjs(event.startDate.toJSDate()).tz(tzid).format("Z");
-            const tzoffsetto = dayjs(event.endDate.toJSDate()).tz(tzid).format("Z");
+              // get timezone offset
+              const tzoffsetfrom = dayjs(event.startDate.toJSDate()).tz(timezoneToUse).format("Z");
+              const tzoffsetto = dayjs(event.endDate.toJSDate()).tz(timezoneToUse).format("Z");
 
-            // set timezone offset
-            standard.addPropertyWithValue("tzoffsetfrom", tzoffsetfrom);
-            standard.addPropertyWithValue("tzoffsetto", tzoffsetto);
-            // provide a standard dtstart
-            standard.addPropertyWithValue("dtstart", "1601-01-01T00:00:00");
-            timezoneComp.addSubcomponent(standard);
-            vcalendar.addSubcomponent(timezoneComp);
-          } catch (e) {
-            // Adds try-catch to ensure the code proceeds when Apple Calendar provides non-standard TZIDs
-            console.log("error in adding vtimezone", e);
+              // set timezone offset
+              standard.addPropertyWithValue("tzoffsetfrom", tzoffsetfrom);
+              standard.addPropertyWithValue("tzoffsetto", tzoffsetto);
+              // provide a standard dtstart
+              standard.addPropertyWithValue("dtstart", "1601-01-01T00:00:00");
+              timezoneComp.addSubcomponent(standard);
+              vcalendar.addSubcomponent(timezoneComp);
+            } catch (e) {
+              // Adds try-catch to ensure the code proceeds when Apple Calendar provides non-standard TZIDs
+              console.log("error in adding vtimezone", e);
+            }
+          } else {
+            console.error("No timezone found");
           }
         }
         const vtimezone = vcalendar.getFirstSubcomponent("vtimezone");