After going undrafted in the 2019 NBA draft, Bigby-Williams was signed by the Charlotte Hornets but quickly released, instead joining the New Orleans Pelicans. Bigby-Williams was signed by the Pelicans on 6 August 2019 to an Exhibit 10 contract. After playing in one preseason game, he was waived on 19 October. He joined their affiliate in the NBA G League, the Erie BayHawks. On 10 January 2020, Bigby-Williams missed a game with an undisclosed injury. He posted 18 points, 12 rebounds, six blocks, one assist and one steal in a loss to the Iowa Wolves on 23 January. Bigby-Williams averaged 8.5 points, 9.2 rebounds and 2.1 blocks per game in 25 games. On 4 February, he was traded to the Sioux Falls Skyforce in exchange for Raphiael Putney. On 27 February, Bigby-Williams was traded to the Fort Wayne Mad Ants in exchange for a 2020 2nd round pick and the rights of Isaiah Hartenstein.