MacArthur signed a one-year deal for $1.1 million with the Toronto Maple Leafs on August 28, 2010, ahead of the 2010–11 season. When asked later about his decision to sign in Toronto, MacArthur said, "It was nice to come back to a hockey community." He later added, "It's the most fun I've had since junior." Maple Leafs captain Dion Phaneuf, one of MacArthur's teammates at the 2005 World Junior Championships, was influential in the decision to sign with Toronto. MacArthur scored goals in each of his first four games with the club, becoming the first player in team history to do so. The following month, he tied his personal career-best when he scored two goals against the Pittsburgh Penguins on October 13. On November 16 he tied a club record by recording three assists in a period against the Nashville Predators. At the end of his first season with the Maple Leafs, he signed a two-year contract extension at $3.25 million per annum on July 5, 2011, thereby avoiding salary arbitration with the club.