Allen first signed for the
Plymouth Argyle Centre of Excellence at the age of 11, going on to represent Plymouth Argyle's under 18s as an apprentice. He signed his first professional contract for the club in 2014. He made his first appearance for the club as a 107th-minute substitute for
Lee Cox in a League Cup first-round game against
Leyton Orient on 12 August 2014, in which he took and scored the first Argyle penalty in the
penalty shootout after a 3–3 draw at
Home Park. Four days later, he made his first league appearance in the Devon Derby against
Exeter City, as a 76th-minute substitute for
Tyler Harvey in Argyle's 3–0
League Two home win. In March 2015, after completing a month-long loan at
Gosport Borough in the
Conference South, Allen signed for
Southern League club
Truro City until the end of the 2014–15 season. He made his Truro debut as a substitute in the 2–1 win at
Chippenham Town on 21 March. Allen was released by
Plymouth Argyle manager
John Sheridan on 17 May 2015 along with a number of other first team players. Sheridan promptly resigned from his position only days later. On 1 June 2015, it was announced that Allen had gone on trial at
National League side
Gateshead, and on 11 June he played in a pre-season friendly against
Premier League side
Newcastle United. On 28 June, Allen signed a one-year contract with Gateshead. He made his Gateshead debut on 26 September as a substitute in a 1–0 victory at
Forest Green Rovers. After starting the three of the following four matches, Allen did not feature for the first team again before his contract was cancelled by mutual consent on 14 January 2016. In February 2016, Allen returned to
Cornwall and signed for
South West Peninsula League Premier Division side
Bodmin Town. He made his debut on 20 February in a 2–0
Cornwall Senior Cup victory over Mousehole A.F.C. and scored his first senior goal in the semi-final of the same competition on 1 March in a 5–2 win over
Helston Athletic. In the summer of 2018, he signed permanently for
Tiverton Town. On 6 October 2018, he returned to Truro City. In June 2019, he returned to Tiverton Town after being released by Truro City. In August 2020, he announced that he was leaving Tiverton due to work commitments, as he had started a new career as a trainee financial advisor and could not devote the necessary time to travelling. He subsequently dropped down a couple of divisions to play for
South West Peninsula League side
Plymouth Parkway for the 2020–21 season before it was curtailed. At the end of the season the club were awarded upward movement into the Southern League. In August 2022, Allen returned to Tiverton Town. ==Career statistics==