The 23-year-old striker moves to the Stadium of Light from Everton on season-long loan, and is Lee Johnson's sixth addition this summer.
Broadhead made his first-team debut for the Toffees in December 2017 in a Europa League tie against Apollon Limassol, with his Premier League debut coming last season away at Brighton & Hove Albion.
The Wales Under-21 international spent the 2019-20 season on loan in Sky Bet League One with Burton Albion, featuring 22 times and scoring three goals.
Broadhead said: “It’s been a mad 48 hours from being on the bench for Everton to arriving in Sunderland, but I’m so happy to be here. I’v