The 26-year-old, who made his name at Sunderland and has 27 caps for the Republic of Ireland, joined the Latics two years ago but appears to be on his way back to the Premier League with the Baggies.
He played 37 times for Wigan last season but could not prevent the club sliding into League One – Gary Caldwell’s side finishing in 23rd place some seven points from safety.
McClean, who was born in Derry and went on to play for Derry City, arrived in England in 2011 when Sunderland manager Steve Bruce paid the League of Ireland club £350,000 for his services.
He soon established himself at the Stadium of Light and was handed an international debut by Giovanni Trappatoni on 29 February 2012 – coming on as a substitute in a friendly against the Czech Republic in Dublin.
Wigan had already rejected two bids from West Brom but McClean now seems set to become part of Tony Pulis’ squad for next season, subject to agreeing personal terms and passing a medical.