Stringer made his AFL debut against Adelaide in round 4 of the 2013 AFL season. In 2014, Stringer's abilities improved dramatically. This led to him receiving a nomination for the Nab Rising Star in round 20, after a match winning 4 goals against St Kilda Saints. In 2015, Stringer had his breakthrough season kicking 56 goals and averaging 14 disposals per game, cementing himself as one of the competition's most exciting young players. Stringer also played every game in the 2015 season except for one. He was given "The Package" as his nickname after BT saw him in the shower. Stringer's outstanding season was capped off with an All-Australian selection. He later represented Australia in the 2015 International Rules game. In 2016, Stringer struggled with form which led to him being dropped at the end of the Home and Away season. Despite inconsistent form Stringer still kicked the most goals for the Bulldogs that year, 37. Stringer returned for the Bulldogs elimination Final against the Eagles, kicking one goal in the Bulldogs 47 point thrashing of the Eagles at Domain Stadium. He then played in the Dogs 23 point win over Hawthorn, contributing immensely kicking 3 goals. In the final minute of Preliminary Final when the Dogs were leading by just 5 points, Stringer had the ball inside the attacking 50 and instead of having a shot for goal he crossed to teammate Tory Dickson. Dickson was then able to take time off the clock and then shoot just after the siren was called. This act of selflessness by Stringer helped slow down play and landed the Bulldogs into their first Grand Final in 55 years. In the 2016 AFL Grand Final the Bulldogs took on the minor premiers, Sydney Swans. Stringer had a quiet game, but kicked an important goal in the final term to stretch the Dogs lead over Sydney. The Bulldogs defeated Sydney by 22 points and won their 2nd Premiership in the club's history. On 14 April 2017 Stringer made history by kicking the first ever AFL goal on a Good Friday. Stringer was contracted until the end of the 2018 season, but at the end of the 2017 season Bulldogs coach Luke Beveridge confirmed that the club was looking to trade him. He was officially traded to Essendon during the trade period. At Essendon, he has regained his form despite a slow start to win the club's goalkicking award with 30 goals. He was forced to play as the number one forward for most of the year, with tall forwards Joe Daniher and Shaun McKernan falling to injury.
