On February 2, 2017, the Steelers signed Boswell to a one-year, exclusive-rights contract. In Week 2, against the Minnesota Vikings, Boswell converted four field goals and two extra points in the 26–9 victory. In Week 7, He kicked a season-high five field goals against the Cincinnati Bengals. In Week 11, he kicked four field goals in a 40-17 win against the Tennessee Titans. Boswell made a game-winning 53-yard field goal in Week 12 (November 26, 2017) to beat the Green Bay Packers 31-28 as time expired. His game-winner set a new career-long and tied kicker Dan Bailey's record set in 2016 for the longest NFL field goal ever kicked at Heinz Field (53 yards) in its 17-year history. The only longer successful attempt was in collegiate play when former Old Dominion kicker Jarod Brown made a 54-yard kick against the Pitt Panthers in 2013. In Week 13, Boswell converted both extra points and all three field goal attempts, including a 38-yard game-winner as time expired, in a 23–20 comeback win over the Bengals, earning him AFC Special Teams Player of the Week. The next week he kicked four field goals including a game-winner against the Baltimore Ravens. Throughout the season, Boswell has kicked multiple game-winning field goals in the last minutes, earning him status as one of the Steelers' "Killer B's" and a spot on the AFC's Pro Bowl starting roster. He finished the season tied with Harrison Butker for fourth in scoring with 142 points.