Portland Inlet is an inlet of the Pacific Ocean on the north coast of British Columbia, Canada, approximately 55 km (34 mi) north of Prince Rupert. It joins Chatham Sound opposite the Dixon Entrance. It is 40 km (25 mi) long and as much as 13 km (8.1 mi) wide. It drains the Portland Canal, Nass Bay (outlet of the Nass River), and Khutzeymateen Inlet, among others, and is the site of Pearse Island and Somerville Island. Other major sidewaters of the inlet are Observatory Inlet and its east arm, Alice Arm.

Portland Inlet was mapped by the Vancouver Expedition in 1793 and named Brown Inlet, with George Vancouver later changing the name to honour the British House of Portland.