Grzegorz Sandomierski

Jagiellonia Bialystok

Sandomierski's career began at Jagiellonia Białystok, starting in the reserve side from 2006. He played in four games and then was loaned out to Lech Poznań. He made two appearances in the fourth division, after which he returned to Jagiellonia. In the 2007–08 season, due to an injury to Jacek Banaszyński, Sandomierski made his Ekstraklasa debut against Cracovia in which he conceded two goals. By the end of the competition, he appeared in four other matches. Sandomierski then sustained a serious injury which excluded him from play for half a year. In January 2009, he was loaned to Ruch Wysokie Mazowieckie, where he played as a first choice goalkeeper. Prior to the 2009–10 season, he returned to Białystok. Sandomierski got his chance for Jagiellonia after Rafał Gikiewicz suffered a poor run of form. During his time at Jagiellonia, for six matches in a row, Sandomierski kept a clean sheet. His streak lasted 564 minutes, a club record, and ended in a clash with Ruch Chorzów.

Genk

In August 2011, Sandomierski signed a five-year contract with Belgian champions Genk, as a replacement for Thibaut Courtois.

Blackburn Rovers

On 31 August 2012, Sandomierski signed on a season long loan with Blackburn Rovers with a view to signing long-term. He made his debut for Rovers against Cardiff City in a 3–0 defeat conceding two goals one of which was a penalty, coming on for injured counterpart Jake Kean in the 52nd minute. Sandomierski's…

On 13 January 2023, at the age of 33, he ended his professional football career. In July 2023, he joined Jagiellonia Białystok's under-19 team and KS Turośnianka as a goalkeeping coach. In June 2024, he left Turośnianka to focus on his duties at Jagiellonia. A year later, he was promoted to the role of assistant goalkeeping coach for Jagiellonia Białystok's senior team. In August 2025, Sandomierski joined the Poland under-18s' coaching staff.

Jagiellonia Białystok

Polish Cup: 2009–10 Polish Super Cup: 2010 Dinamo Zagreb

Prva HNL: 2013–14 Zawisza Bydgoszcz

Polish Super Cup: 2014 CFR Cluj

Liga I: 2019–20, 2020–21 Supercupa României: 2020 Individual

Polish Newcomer of the Year: 2010 Ekstraklasa Player of the Month: October 2009, March 2015