- St. Mirren (2015)
- Peterborough Unired (2015-16)
Sadlier, born in Haywards Heath in England, began his career with West Ham United and spent ten years with The Iron coming through to appear for their under-21 side.
He left to move to Scottish Premiership side St. Mirren in February 2015 playing 11 times until the end of the season and scoring in a win over Kilmarnock.
Dave Robertson signed him for Peterborough United in the summer and he made his debut in a League Cup tie against Charlton Athletic.
Sadlier went to Halifax Town for a loan spell in October that ended this weekend.
Sadlier has been a regular part of Ireland underage squad from under-15 level right up to under-21.
He holds 22 caps with two goals to his name across the various age levels.
After just seven games he extended his contract at The Showgrounds to the end of 2017.