Melvine Malard, Keira Walsh and Maika Hamano were on target as Sonia Bompastor’s side extended their unbeaten start to the league campaign.
Malard breaks West Ham resistance
Chelsea dominated possession from the opening stages but initially struggled to turn their pressure into clear chances.
The breakthrough finally arrived in the 38th minute after Sjoeke Nüsken pressed West Ham into making a mistake in midfield.
Nüsken won possession and set up Malard, who held off the challenge before turning and firing a composed finish into the bottom corner.
Chelsea went into half-time 1-0 ahead, with West Ham failing to register a shot on target in the opening 45 minutes.
Walsh doubles Chelsea's advantage
West Ham continued to frustrate Chelsea after the interval, but the visitors eventually found the second goal with 10 minutes of normal time remaining.
Alyssa Thompson created the opening with a run from the left before Wieke Kaptein laid the ball off for Keira Walsh.
The England midfielder made no mistake from the edge of the penalty area, firing into the bottom corner to make it 2-0.
It was Walsh's third WSL goal of the season, according to Sky Sports.
Hamano seals emphatic victory
Chelsea added a third goal in the 87th minute to complete a thoroughly deserved victory.
Thompson again provided the attacking impetus from the left, with her effort saved before substitute Aggie Beever-Jones collected the rebound and sent the ball towards the far post.
Maika Hamano reacted quickest and headed home to make it 3-0.
The goal capped a superb first start of the season for the Japan international, who had been handed a place in the starting XI by Bompastor.
Chelsea move top of the WSL
The victory moved Chelsea to the top of the Women's Super League, although Manchester City had a game against Arsenal later on Sunday.
Chelsea had entered the match with 10 points from their opening four league fixtures after beating Manchester United, Birmingham City and Arsenal, alongside an opening-day draw against Aston Villa.
The Blues have also now kept six consecutive clean sheets in all competitions.
West Ham, meanwhile, were unable to register a shot or touch the ball inside Chelsea's penalty area during the match, underlining the visitors' defensive dominance.
Match summary
• Chelsea: Melvine Malard 38', Keira Walsh 80', Maika Hamano 87'
• West Ham United: No goals
West Ham United 0-3 Chelsea
What's next for Chelsea?
Chelsea's players will now join up with their respective national teams during the international break.
The Blues return to WSL action on 18 October when they host Tottenham Hotspur at Stamford Bridge.