Atlanta Hawks (2018–2019) On June 21, 2018, Spellman was selected by the
Atlanta Hawks with the 30th overall pick in the
2018 NBA draft. He was the third of four Villanova players drafted that year, as well as the last of their first round selections there. Spellman signed with the Hawks on July 1, 2018. On December 30, 2018, Spellman was assigned to the Hawks’
NBA G League affiliate, the
Erie BayHawks. He made his G League debut the next night, scoring 28 points and collecting 14 rebounds in a loss.
Golden State Warriors (2019–2020) On July 8, 2019, Spellman was traded to the
Golden State Warriors for
Damian Jones and a 2026 second round draft pick.
Iowa Wolves (2020) On February 6, 2020, Spellman was traded to the
Minnesota Timberwolves, along with
D'Angelo Russell and
Jacob Evans, in exchange for
Andrew Wiggins and a first round pick. After being traded, Spellman was assigned to the Timberwolves' G League affiliate, the
Iowa Wolves. He recorded a
triple-double with the Wolves on March 8, posting 18 points, 14 rebounds, and 12 assists in a 115–112 loss to the
Santa Cruz Warriors. He did not play any games for the Timberwolves.
Erie BayHawks (2021) On November 24, 2020, Spellman was traded to the
New York Knicks in exchange for
Ed Davis. On January 7, 2021, he was waived by the Knicks. On January 26, 2021, Spellman signed with the
Erie BayHawks of the NBA G League.
Anyang KGCAnyang Jung Kwan Jang Red Boosters (2021–2023) Spellman joined the
Chicago Bulls for the
2021 NBA Summer League. On August 31, 2021, Spellman signed with
Anyang KGC of the
Korean Basketball League. In March 2023, Anyang KGC played in the
EASL Champions Week, and won the gold medal. Spellman was named the Champions Week' MVP. On December 12, his contract was terminated, replacing by
Robert Carter.
Zenit Saint Petersburg (2024–2025) On July 31, 2024, Spellman signed with
Zenit Saint Petersburg of the
VTB United League. On January 21, 2025, his contract was terminated.
Wonju DB Promy ( feb 2025– september) On February 10, 2025, Spellman signed with
Wonju DB Promy of the
Korean Basketball League (KBL), replacing
Robert Carter. ==National team career==