In the 2015–16 season, Simpson started the season well in League Two when he scored the opening game of the season, in a 2–0 win over Barnet. He then scored three goals in three consecutive matches throughout August against Stevenage, Newport County and Bristol Rovers. After scoring two times throughout September, Simpson, again, scored five goals in four matches, including a brace against Crawley Town on 10 October 2015. By the end of 2015, Simpson scored nine goals in ten matches against York City (twice), Plymouth Argyle, Wimbledon, Mansfield Town, Portsmouth, Bristol Rovers and Stevenage (twice). As a result of his performance, Simpson was named Sky Bet League Two Player of the Month for November. After scoring two goals by the end of January, Simpson went on a goal drought throughout February and didn't score again in a 2–2 draw against Carlisle United and scored a brace in a 3–2 win over Dagenham & Redbridge on 16 April 2016. A week later, however, Simpson was sidelined for a week, due to back injury. Up until this point, Simpson remained an ever-present player since the start of the season. At the end of the 2015–16 season, Simpson went on to make forty-eight appearances and scoring twenty-five goals in all competitions, finishing as the second's top-scorer behind Matty Taylor. For his performance, Simpson was named the fifth best player in League Two and Football League Two PFA Team of the Year. In addition, Simpson was named Away Player of the Year award at the 20th annual Supporters' Club Dinner-Dance.