Stina Blackstenius scored the game’s first goal while rotating while holding the ball on her chest.
Six minutes later, after Liverpool goalkeeper Rachel Laws parried the forward’s shot, Caitlin Foord scored the second goal by heading it in.
Leah Williamson was adjudged to be offside just before Blackstenius scored the opening goal, despite Arsenal’s best efforts.
The Gunners are still fourth in the standings, but with a game remaining, they are now three points behind third-place Manchester City.
Liverpool remains in seventh place but is still winless on the road.
Arsenal vs. Liverpool and Chelsea vs. Brighton reactions
Arsenal maintains its form following a cup victory.
On Sunday at Selhurst Park, Arsenal had to come from behind to defeat Chelsea and win their first trophy in four years.