A brace from Aritz Aduriz and late goals from Ibai Gomez and Markel Susaeta saw Ernesto Valverde's men end a three-game winless run.
The win lifted Bilbao into eighth in the table, eight points adrift of Villarreal – who are sixth and occupy the final European place.
Getafe, who sit 13th and eight points clear of the bottom three, were reduced to 10 men in the 44th minute when Emiliano Velazquez saw red, and it proved costly.
Velazquez denied Bilbao an obvious goalscoring opportunity just before the break, and Aduriz sent Vicente Guaita the wrong way from the penalty spot.
Aduriz doubled Bilbao's advantage early in the second half with a good finish after being played through by Andoni Iraola.
The hosts needed until late on to seal the win, with Ibai heading in a Susaeta cross before the latter tapped in the fourth.
