Los Leones opened the scoring in the 27th minute when Oscar De Marcos slotted into the lower left of the net after intercepting Jesus Navas's pass and finishing with a right-footed shot.
Markel Susaeta scored a right-footed shot for Athletic Bilbao in the 46th minute to double their lead.
The Basques suffered a setback when midfielder Ander Herrera was given a red card in the 76th minute.
Sevilla striker Alvaro Negredo scored in the 78th minute but the visitors were unable to equalise.
Athletic Bilbao are in 12th place, and in striking distance of Levante in sixth with a record of four wins, five losses and two draws leaving them three behind after 11 games.
With 15 points Sevilla trail Levante by two for the final Europa League spot, and have compiled a record of four wins, four losses and three draws on the season.