With your Office 365 email account, you can send a sharing invitation to other users so they can view your calendar in their own Calendar list.
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Once you open Outlook, you will find the calendar icon at the bottom left of your screen.
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Click on the Calendar Icon to open the calendar.
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After the calendar opens, make sure that you are in the home tab ribbon at the top of your screen.
Note: If you do not see the ribbon at the top of your screen, click the down arrow towards the top right to expand the ribbon. -
From here you will click share calendar.
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Select the calendar you would like to share.
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A dialogue box will appear. Make sure you are in the permissions tab and click add.
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Select the user or users that you would like to share your calendar with and click add.
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Click OK.
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Choose which permission you would like to provide to the user, select apply and click OK.
Source: https://support.microsoft.com/en-us/help/10157/sharing-calendar-and-contacts-in-office-365