[3] Ambrose joined Scottish Premier League club Celtic on the summer 2012 transfer deadline day, signing a three-year contract.

[6] Ambrose made his debut on 22 September 2012 as a substitute for Celtic captain Scott Brown against Dundee in the Scottish Premier League, a 2–0 victory.

[9] Ambrose went on to make his Champions League debut for Celtic, where he played 90 minutes in a 3–2 win over Spartak Moscow.

[11] On 7 November 2012, ahead of a Champions League game against Barcelona, Ambrose made a vow to give his best ever performance for the club.

[16] Ambrose made amends in the next league game when he scored Celtic's opener in a 6–2 win over Dundee United.

[18] After the match, which Juventus won 2–0 and progressed to the quarter finals, Neil Lennon stated that Ambrose was late for training and missed the team bus from the hotel and was left to catch up by taxi.

"[20] Ambrose came under strong criticism from fans and pundits alike for frequent poor performances and errors which led to opposition goals.

[23] In February 2017, Ambrose's proposed loan move to Blackburn Rovers fell through, after the club was unable to obtain a work permit.

[35] On 4 February 2022, Ambrose joined Scottish Championship side Dunfermline Athletic on loan until the end of the 2021–22 season.

[37] Ambrose would make his debut against Inverness Caledonian Thistle, notably being named man of the match after Morton's subsequent 4–0 victory.

[39] Ambrose made a total of 14 appearances for Morton in all competitions, before it was announced that he would be leaving the club upon the expiration of his contract.

[40] On 8 June 2024, Ambrose joined North West Counties Football League Premier Division side Bury.

Having continued to live in Scotland, the commute to Bury no longer proved to be a viable option for Ambrose and his family.