Arsenal made it eight wins in a row as they moved three points clear of Manchester United in the race for the third Champions League place with victory over struggling West Ham.
The Gunners were rarely troubled defensively and deservedly led at the break through Vivianne Miedema.
She showed typical class to create space on the edge of the box before curling a shot into the top corner.
Kim Little raced through and delicately dinked a second goal to clinch the win.
Defeat leaves West Ham just two points clear of bottom-of-the-table Bristol City with two games remaining.
Arsenal’s focus remains at the other end of the table and finishing in the final spot in Europe’s premier competition for next season, and their vastly superior goal difference effectively means one win will guarantee it.
But they still should have added to a goal difference that now stands at plus 47.
Caitlin Foord had an early header tipped over by fellow Australian Mackenzie Arnold and Miedema teed up Jordan Nobbs, who shot just wide.
Nobbs also found the net from an offside position and Netherlands striker Miedema shot into the side netting before her delightful strike made it 1-0.
The chances continued to fall the way of the home side but it was not until Little pounced with 12 minutes left that victory was as good as sealed.
West Ham, who remain winless in all their 14 WSL London derbies, almost got back into the game when Lydia Williams had to make a superb save to palm away a Martha Thomas header.
But Arsenal stood firm to make it eight games without conceding since losing to Chelsea in February.
16MaritzSubstituted forPattenat 85′minutes
9MeadSubstituted forvan de Donkat 86′minutes
8NobbsSubstituted forRoordat 72′minutes
19FoordBooked at 51mins
7van de Donk
West Ham Women
2KvammeSubstituted forDentonat 81′minutes
26CousinSubstituted forThomasat 56′minutes
Match ends, Arsenal Women 2, West Ham United Women 0.
Second Half ends, Arsenal Women 2, West Ham United Women 0.
Hand ball by Martha Thomas (West Ham United Women).
Attempt missed. Leah Williamson (Arsenal Women) header from the centre of the box misses to the left. Assisted by Kim Little with a cross following a corner.
Corner, Arsenal Women. Conceded by Grace Fisk.
Attempt blocked. Daniëlle van de Donk (Arsenal Women) right footed shot from the centre of the box is blocked. Assisted by Anna Patten.
Offside, Arsenal Women. Daniëlle van de Donk tries a through ball, but Jill Roord is caught offside.
Attempt saved. Kim Little (Arsenal Women) right footed shot from the left side of the box is saved in the centre of the goal. Assisted by Vivianne Miedema.
Substitution, Arsenal Women. Daniëlle van de Donk replaces Beth Mead.
Substitution, Arsenal Women. Anna Patten replaces Noëlle Maritz.
Attempt saved. Martha Thomas (West Ham United Women) header from the centre of the box is saved in the top left corner. Assisted by Anouk Denton with a cross.
Substitution, West Ham United Women. Anouk Denton replaces Cecilie Kvamme.
Goal! Arsenal Women 2, West Ham United Women 0. Kim Little (Arsenal Women) right footed shot from the right side of the six yard box to the bottom left corner. Assisted by Noëlle Maritz.
Attempt blocked. Emily van Egmond (West Ham United Women) right footed shot from the centre of the box is blocked.
Attempt blocked. Martha Thomas (West Ham United Women) header from the centre of the box is blocked. Assisted by Kenza Dali with a cross.
Corner, West Ham United Women. Conceded by Kim Little.
Attempt blocked. Beth Mead (Arsenal Women) right footed shot from outside the box is blocked. Assisted by Kim Little.
Substitution, Arsenal Women. Jill Roord replaces Jordan Nobbs.
Corner, Arsenal Women. Conceded by Mayumi Pacheco.