The award has gone to a Liverpool or City player for five straight seasons. City defender Ruben Dias won last year.
The women’s award, introduced in 2018, was open to the full FWA membership for the first time. It was previously decided by an expert panel.
Kerr captured 40% of the vote, ahead of Arsenal striker Vivianne Miedema and Manchester City forward Lauren Hemp.
The Australia star has scored 18 goals in the Women’s Super League for first-place Chelsea and 28 goals in total. Her club teammate Fran Kirby won last year.
The awards will be presented at an FWA dinner next Thursday.
“Both Mo and Sam have been outstanding this season, breaking records for both club and country,” FWA chair Carrie Brown said. “As well as their performances on the pitch, they are leaders and standard bearers of excellence at their clubs and respective leagues.
“The fact they have won by such convincing margins underlines just how impressive they have been this season which has been recognized by our members.”