A late change for the Gunners had Sead Kolasinac entering in place of Kieran Tierney, who got injured in the pre-match warm-up while West Ham's Jack Wilshere unavailable against his former side.
Following a tough opening spell, the Gunners broke the deadlock 25 minutes gone after Alexandre Lacazette made a late run in the box to head home Pierre-Emerick Aubameyang’s cross.
Bukayo Sak, in for his first start of the season, missed a glorious chance to double the Gunners’ lead on the half-hour mark after hoofing over the top from an unmarked position and goal in sight.
That missed chance would not go unpunished as Michail Antonio beat Gabriel Magalhaes to a low cross from the right on the cusp of halftime for an easy finish.
West Ham were out promising in the second half and nearly went in front from a probing delivery from the left, but Leno parried comfortably in the end.
The Gunners heralded a substitution after Willian made way for Ivorian winger Nicolas Pepe following the midway stage in the second half.
West Ham still maintained momentum moments later after Antonio headed onto the woodwork following a looping ball from the left.
Mikel Arteta’s charges sprung alive five minutes to the end and regained the lead after a through ball released Dani Ceballos who played a first-time cross for Eddie Nketiah to tap home.
Aubameyang went in search for his second of the campaign, but was unable to beat Lukasz Fabianski as the Gunners claimed successive wins in the league.
