The Gunners, who were in their worst type since 1977, went behind once Angelo Ogbonna’s header deflected in off defender Ainsley Maitland-Niles.
Gabriel Martinelli equal once he Lashed on Sead Kolasinac’s pull-back.
Arsenal’s record signing Nicolas Pepe curled in an exceedingly fine second, then originated Pierre-Emerick Aubameyang for a third.
The Gunners had not won since a 3-2 success over Portuguese aspect Vitoria de Guimaraes within the Europa League on twenty-four October and ravaged Unai Emery last month.
Former Arsenal midfielder Ljungberg, in temporary charge in his initial managerial role, had seen his team draw 2-2 at Norwich and lose 2-1 reception against Brighton on Thursday.
The Gunners did not have a trial on target in the gap hour before 3 goals in 9 minutes turned the match around at the London sports stadium.
This result conjointly will increase the pressure on West Ham boss Manuel Pellegrini, with the Hammers sixteenth, just one purpose higher than all-time low 3, and with just one win in eleven matches.
Arsenal jumped up from eleventh to ninth, seven points behind fourth-placed Chelsea however twenty-four adrift of Premier League leaders Liverpool.
The only negatives for the Gunners w
ere 3 injuries as right-back Hector Bellerin was hurt within the tune-up, left-back Kieran Tierney went off with a shoulder drawback and midfielder Granit Xhaka went off late on with a head injury.