He started the season-opener against the New England Patriots and caught eight passes for 84-yards in a 28–21 loss. On November 1, 2015, Miller caught ten passes for a season-high 105 receiving yards in a 16-10 loss to the Cincinnati Bengals. On November 15, 2015, Miller was named the backup quarterback against the Cleveland Browns after the starting quarterback Landry Jones sprained his ankle. Although Roethlisberger was still injured, he came in to finish the game with Miller as the emergency backup quarterback. In Week 12, Miller suffered a rib injury during the second quarter of a 39–30 loss to the Seattle Seahawks. He missed the next game with the injury. During a Week 14 contest against the Cincinnati Bengals, he caught a season-high ten passes for 60 yards and had his second career carry for a two-yard gain in a 33-20 victory. On January 3, 2016, he made three catches for 18 yards and caught his last career touchdown on a two-yard pass from Ben Roethlisberger during the Steeler's 28-12 victory. He finished his last season with 60 receptions for 535 receiving yards and two touchdowns in 15 games and 15 starts.