Sessegnon, 29, signed a three-year contract on transfer deadline-day after Albion surpassed an undisclosed transfer fee which allowed Shane Long to join from Reading in August 2011.
The availability of the Benin international, who left Paris Saint-Germain in a £6million move to Sunderland in January 2011, will be a big boost to manager Steve Clarke, with Republic of Ireland forward Long likely to be missing again with a knee problem.
Gareth McAuley headed the club's first league goal of the season against Fulham and, in his first full season at the Stadium of Light, Sessegnon finished as their eight-goal joint-leading scorer.
He managed seven goals in 39 appearances in his second campaign with the Black Cats and has made 40 appearances and scored eight times for Benin and featured in the 2008 and 2010 Africa Cup of Nations.
In total, Sessegnon has made 294 career league appearances, including 30 as a substitute, scoring 42 goals.