The Mirror says experienced midfielder Sidwell was in London for a medical and is sorting out personal terms on a move that will end his stay at Villa and give him first-team football.
Sidwell is joining for the start of the window as Hammers know there is no time to lose in their bid to stay up. The cost of the deal will depend on their survival this season - and in the future.
Hammers will pay a small sum up front, with extras on bonuses. But the move makes sense if Sidwell can bring some extra drive and experience to their small squad.