The Baggies are expected to officially anounce the signing of the Germany-born Ghanaian tomorrow after the Foxes accepted their £12m offer.
Schlupp made 24 appearances in Leicester's title-winning season last year, but has seen himself fall behind Mahrez, Albrighton and Kapustka in the pecking order at the King Power Stadium.
The 23-year-old was not even on the bench for Leicester's 2-1 opening day defeat to Hull and is widely expected to be a West Brom player within the next 24 hours.