The visitors threatened to cause an upset when Kelly Gago burst down the left wing in the 51st minute and unleashed a fine effort into the top corner against the run of play.
Everton looked good value for a point until the third minute of added time when James unleashed a long-range effort with her left foot that clipped the post and found the back of the net.
Frida Maanum and Alessia Russo doubled the hosts' lead before the hour mark and Emily Fox rounded off a big win in style with a spectacular fifth in the final minute.
Elsewhere, Chloe Kelly marked her return to Arsenal by featuring in a crushing 5-0 win over north London rivals Tottenham at the Emirates Stadium.
Lauren James grabbed a stoppage-time winner as Chelsea battled from a goal down to beat Everton 2-1 at Kingsmeadow and maintain their seven-point lead at the top of the Women's Super League.
