Josh Lelan started his career within Derby County's youth system but went on to sign an extended scholarship. Lelan's first taste of senior football came when he joined Football Conference side Gateshead on a months loan in September 2013. He made his debut in the 1–0 win over Tamworththree days later. Lelan returned to his parent club after making four appearances for Gateshead. On 23 July 2014, Lelan joined Swindon Town on a one-month young loan. He made his debut on the opening day of Swindon's 2014–15 campaign at home to Scunthorpe United. On 29 August 2014, Lelan extended his loan at Swindon by a further month, which would see him stay at the club until 27 September 2014. Lelan made five appearance for the club, as he was recalled by his parent club. At the end of the 2014–15 season, Lelan was released by the club.
After being released by Derby County, Lelan joined Football League Two side Northampton Town on a 12-month contract At the end of the 2015–16 season, Lelan was released by Northampton Town. Northampton manager Rob Page expressed regret after his decision to release Lelan, saying "the lad has gone in and given a good account of himself. From a supporters' view it might be a little bit of a surprise, but we have made the decision as a group and what we think is best for this football club." In July 2016, Lelan, in search of a new club, played as a trialist for League One team Gillingham in a 2–1 win over Concord Rangers and League Two team Plymouth Argyle in a 9–0 win over St Blazey. Lelan was reported to be attending trials at Swedish 3rd tier side Västerås SK on 11 August 2016. On 2 December 2016, he was on trial with League Two side Leyton Orient playing against Southend United in a behind-closed-door friendly.
On 26 January 2017, Lelan joined League Two side Crawley Town on a one-and-a-half-year deal after a short-term trial spell back at Derby County. On 4 February 2017, Lelan made his Crawley debut in their 2–1 home defeat against Stevenage. Featuring for the full 90 minutes, Lelan was awarded Crawley Town's man of the match after an impressive debut despite the defeat. On 14 May 2018, it was announced that Lelan would leave Crawley at the end of his current deal in June.
Aldershot Town
On 2 July 2018, following his release from Crawley, Lelan agreed to join National League side Aldershot Town. He was released at the end of his first season at the club.
International career
On 5 August 2016 Lelan received his first call up for the Kenyan national team. He made his international debut on 30 August 2016 in a match against Uganda coming in as a sub
