After a disappointing performance in the side's 3–0 defeat to Portsmouth, McCarthy found the net on his debut at Ewood Park against Everton on 23 August 2006. McCarthy further endeared himself to Rovers fans, scoring a goal on his European debut for the club in a 2–2 against Red Bull Salzburg in the UEFA Cup, and scoring another in the return leg. He finished second top scorer in the Premier League in 2006–07 with 18 league goals, as well as 24 in all competitions.