Danielle van de Donk scored a hat-trick for the hosts, while former Sunderland striker Beth Mead scored on her debut.
Chelsea, who lost to Arsenal in last year's final, also cruised into round six with a 7-0 win over Doncaster.
Bristol City beat Millwall 5-0, while wins for Liverpool, Notts County, Birmingham and Sunderland ensured an all-WSL 1 quarter-final line-up.
Liverpool Ladies beat Merseyside rivals Everton, with Shanice van de Sanden scoring the winner in extra time after the teams had finished the 90 minutes level at 1-1.
Birmingham Ladies beat West Brom 2-0 in Marc Skinner's first game in charge, while Notts County and Sunderland progressed with narrow wins over Yeovil and Aston Villa respectively.
The draw for the quarter-finals will take place on Monday at 11:40 GMT.
Women's FA Cup holders Arsenal Ladies thrashed local rivals Tottenham 10-0 to reach the quarter-finals.