Andriy Yarmolenko gave the visitors the lead in the first-half, before Mark Noble made it two with the last kick of the opening period on Thursday night.
Rapid Vienna never really threatened a comeback, and David Moyes’ side go into their final group stage match knowing top spot is already sewn up.
West Ham very nearly took the lead after just six minutes. Arthur Masuaku played a lovely first-time ball into the box, and Jarrod Bowen’s poked effort rolled just wide of the far post.
Rapid Vienna held firm and started to grow into the game, but a five-minute spell just before the break put the Hammers in complete control.
Nikola Vlasic worked the ball well on the left wing before standing up a cross to the far post, where Yarmolenko was on hand to head home the opening goal.
And with the final action of the half, Yarmolenko was brought down in the box, with Noble making no mistake from the spot for his first Europa League goal.
Bowen and Tomas Soucek both had the chance to extend the lead in the second-half, but were denied by the goalkeeper.
David Moyes used the opportunity to bring off some of his key men with an eye on this weekend’s trip to face Man City, and gave Sonny Perkins his debut, with the youngster having a shot well saved with his first touch.
West Ham saw out the rest of the match for a comfortable win, and it’s job done in Europe for the Hammers until the last 16 in March.