- Niamh Charles (13')
- Pernille Harder (48')
- Sophie Ingle (64')
- Erin Cuthbert (90'+3')
Having won their two games in hand, Chelsea now have a two-point lead over second-placed Manchester United, who Emma Hayes' side also beat 1-0 in the FA Cup final on Sunday.
Fresh off their third successive FA Cup final win, Chelsea needed just 13 minutes to take the lead, when Charles tapped in at the back post.
Chelsea could have extended their lead sooner but after an early penalty claim was turned away for a potential handball, the Blues saw two more appeals for clumsy challenges refused by referee, Louise Saunders, before the first half was over.
Against a West Ham team who hadn't won in the league since December, the lone goal should have been enough for Chelsea as they dominated the proceedings in Dagenham, but the Blues made sure there was no way back for the Hammers at the start of the second half.
On a tear since returning from a long injury layoff, Harder claimed her fifth goal in three appearances when she was found in the centre of the box by Sophie Ingle.
The Welsh midfielder turned from creator to scorer after the hour when she nodded home from a yard out after Mackenzie Arnold had turned Magda Eriksson's initial ball onto the top of the crossbar.
With Hayes liberally going to her bench throughout the second half to help manage minutes with Chelsea playing their fifth game in 15 days, the second half was far more fragmented.
Still, Chelsea wrapped up the three points thanks to a firm effort from Erin Cuthbert with her third goal in as many league games.
- Louise Saunders