After the season, he declared for the 2016 NBA draft, where the Toronto Raptors selected him in the first round with the ninth overall pick.

Pöltl began drawing interest from several NCAA Division I programs, forcing him to decide between a professional career and a U.S. college education.

In a 2014 interview, Pöltl revealed part of his decision-making process:[2]If I went pro in Europe, I probably wouldn't have a chance to go to a university and get my degree.

Pöltl was impressed that Krystkowiak made the effort to visit him in person, and was intrigued that the 6-foot-10-inch (2.08 m) coach played power forward in the NBA and had a history of developing young big men.

[13] During his rookie season, Pöltl received multiple assignments to Raptors 905, Toronto's G-League affiliate.

[17] On July 18, 2018, Pöltl was traded, along with DeMar DeRozan and a protected 2019 first-round draft pick, to the San Antonio Spurs in exchange for Kawhi Leonard and Danny Green.

[18] In his debut for the Spurs in their season opener on October 17, 2018, Pöltl recorded four points, four rebounds and two assists in eight minutes in a 112–108 win over the Minnesota Timberwolves.

[20] On February 25, 2022, Pöltl posted a career high 28 points along with 11 rebounds, 8 assists, and 2 blocks in a 157–153 win against the Washington Wizards.

[22] On March 17, 2021, Pöltl logged his second consecutive double-double with 20 points and a career-high 16 rebounds in a 106–99 win over the Chicago Bulls.

[26] On February 14, Pöltl scored 30 points, grabbed nine rebounds, and blocked six shots during a 133–123 win over the Orlando Magic.