After a loan spell with Dundee United he moved to Partick Thistle in 2018 and then Queen's Park in 2020 before joining Forfar Athletic in 2021.

[3] Slater made his professional debut for Kilmarnock on 29 December 2012, in an away match against Motherwell coming on as a substitute in a 2–2 draw.

He had just converted a penalty kick to put Kilmarnock 2–0 up, but he was shown a second yellow card after running to celebrate with supporters.

[13] After helping his side to Scottish Premiership survival by beating Falkirk 4–1 on aggregate, on 23 May 2016, Slater announced that he was to leave Kilmarnock.

[15] On 7 July 2016, Slater joined English League Two club Colchester United, signing a two-year contract.

[16] He made his debut for Colchester on 6 August in their 1–1 draw with Hartlepool United at Victoria Park on the opening day of the season.

[17] He scored his first Colchester goal with a free kick in their 2–1 defeat to Plymouth Argyle at Home Park on 29 October.

[18] He was ruled out for the remainder of the 2016–17 season in March 2017 following an operation for a double hernia and groin problems, having scored three goals in 32 games in all competitions.

[19] On 3 January 2018, Slater joined Scottish Championship club Dundee United on loan until the end of the 2017–18 season.

[24] Slater joined Scottish Championship side Partick Thistle on a one-year deal in July 2018.