1. Go to contacts tab in Gmail from the drop down menu.

2. Select all the contacts and Click More -> Export.

3. Answer the two sections as follows.

- Which contacts you want to export?

- All Contacts

- Which export format?

- Outlook CSV Format

This will download a contacts.csv file in your system.

4. Now login to office 365 portal (https://portal.office.com) using your email id and password and from the Dashboard select People     Application.

Now click Manage -> Import contacts and select Gmail.

5. Select Gmail from the menu asking where you want to import contacts from, in the next menu using the browse button upload the conatcts.csv file and click the upload button.

This will upload all the contacts from your csv file.