[1] Jenkins started his career at home town club Stranraer where he played for eight years, he spent a two-year spell at the now defunct "big spenders" Gretna in the SPL before ending his time in Scotland with Greenock Morton.

Turning down a new deal on substantially less money, Jenkins crossed the Irish Sea to sign with part-timers Ballymena United.

His goal was an equaliser to level the game at 1–1, but in their first Irish Cup final in 25 years, Ballymena were ultimately defeated 2–1.

[8] Jenkins won the 2012 County Antrim Shield with Ballymena, the club's first major trophy win since 1989 beating Linfield 4–3 on penalties.

In 2017 Allan scored the first goal in the club's League Cup final victory over Carrick Rangers, Ballymena ultimately won 2–0.

To honour the event, manager at the time, Davie Irons made him captain in the match against Dunfermline.In early 2016 Jenkins became a father to his new daughter Alli on 2 February 2016.