McCarthy worked under Ten Hag for two years at Old Trafford before leaving the club during a coaching shakeup last summer, which has now led him to pen a two-year deal with the Harambee Stars, securing his position in charge of the side for the 2027 Africa Cup of Nations.
McCarthy held two management roles with first division South African sides AmaZulu FC and Cape Town City but now takes over a Kenya side who are currently fourth in their six-team Group F for qualification to the 2026 tournament in North America, five points behind leaders Ivory Coast.
He spoke to the BBC about his new role and his ambitions to take Kenya to the World Cup in 2026, which he says would be an honour.
"Participating in the World Cup, it is one of the most special feelings in the world and I want to give them that.
"With the right mindset and dedication from the players, and the willingness to learn and willingness to give everything they've got for the course,
"I think we can surprise a lot of people by still qualifying for the World Cup.