How Walrus amphibians recovered downed carrier pilots

Could a Supermarine Walrus land on the water, pick up a pilot, and then return to an aircraft carrier?

Yes. Walruses were used as carrier search-and-rescue aircraft and could recover pilots from the sea before landing back aboard.

A Walrus could alight on the water, collect a downed pilot, and fly back to the task force. Later in the war, carriers commonly operated one or two in the search-and-rescue role. The amphibian could return directly to the carrier deck with the recovered aircrew. Whether these landings used arresting cables is left uncertain.