Seattle jumped out to a 24-9 lead in the first quarter and led 42-33 at the break behind 12 points apiece from Stewart and Natasha Howard. The Storm opened the second half on a 17-6 spurt to extend it to a 20-point advantage.
Howard had 16 points and nine rebounds for Seattle (6-2), which won in Los Angeles for the first time since 2015. Jewell Loyd added 10 points, Sue Bird had eight assists and no Storm starter played more than 29 minutes.
Terrell Owens, voted into the Pro Football Hall of Fame in February, and Atlanta Falcons wide receiver Julio Jones sat courtside. Owens said in a statement Thursday that he would not attend the induction ceremony in August.