In Boston, Allen and new teammates Kevin Garnett and Paul Pierce formed a "Big Three" and had immediate success, winning an NBA championship in 2008. He remained with the franchise for five seasons, before departing in free agency to join the Miami Heat for two seasons. In Miami, Allen accepted a reserve role, emphasizing spot-up and clutch shooting, which allowed him to capture another championship in 2013. His clutch three-pointer to tie Game 6 of the 2013 NBA Finals with 5.2 seconds remaining is regarded as one of the most memorable plays in NBA history.