Is there a left luggage facility in Macau Outer Harbour Ferry Terminal?

Well, dear, do not worry about it. There is both automatic and staff service for your luggage there.
For automatic one, 20MOP for the fisrt two hours and then 25 MOP every another 12 hours for small luggage. For big luggage, 25MOP at first and 30MOP then. These lockers are at Arrival Hall and Departure Hall.
For staff service, 10MOP every 6 hours will be charged at the Departure Hall.