Domingos leaves Braga for Sporting
He takes over from Jose Couceiro, who joinied Sporting as managing director in December and became interim coach following Paulo Sergio's departure in February.
Domingos joined Braga in 2009, after spells at Academica and Leiria, and immediately took the club to their best league finish last year when they secured second place.
This season he steered Braga to a surprise Europa League final place, although their run was to end in disappointment when they lost 1-0 to compatriots Porto in last week's final in Dublin.
Sporting have not won the league since 2002 and finished this season without any silverware.