He started his career as a 15-year-old in the AZS Szczecin team. Later on, he continued his youth career in Zastal Zielona Góra, MKS Katarzynka Toruń, and SMS PZKosz Władysławowo.
In 2011, he went to the United States to play for the NCAA Liberty Flames of Liberty University.[2] He was part of the 2012-2013 team who made the NCAA tournament. In 2015, he changed his college, energizing the ranks of the University of Mississippi.[3] In his last year in the NCAA he recorded an average of 9.9 points and 4.3 rebounds.[4]
On 11 October 2020, he signed a one-month deal with MoraBanc Andorra of the Liga ACB.[10] In 2021, Gielo signed with s.Oliver Würzburg and he averaged 9.5 points and 3.1 rebounds per game.
On January 13, 2022, Gielo signed with Peristeri of the Greek Basket League.[11] In 16 league games, he averaged 11.7 points, 3.3 rebounds, 1.1 assists and 0.8 steals, playing around 28 minutes per contest.