Semple began his career with Peterborough United, in which time he spent two weeks training with Manchester United in the summer of 2002 and participating in an International under 17 tournament in Portugal and making his league debut aged 17 years and three months against Bristol City in October 2002. His progress at Peterborough was affected by a broken leg towards the end of the 2002–03 season and, in a bid to recover fitness, he joined Farnborough Townon loan in November 2003, remaining for two months and scoring twice in nine league appearances. Despite his initial promise, Semple struggled to cement a regular place in the Peterborough team and in four season, he would make just 15 league starts, with another 26 appearances from the substitutes bench. In July 2006, Semple left Peterborough to join Lincoln City on a two-year contract. However, he struggled to make an impact with Lincoln: a hamstring injury coupled with a lack of form limited him to just four substitute appearances in the league in his first season whilst a loan spell with Chester City was also unproductive. At the beginning of the 2007–08 season, Semple was loaned to Rushden & Diamonds but, after just four appearances, he returned to Lincoln. In January 2008, having failed to even make the substitutes bench for Lincoln, he was transfer listed by Lincoln's new manager Peter Jackson before he agreed to have his Lincoln contract cancelled at the end of January 2008. In February 2008, he linked up with Oxford United on non-contract terms but the spell lasted only a single appearance and two weeks before he was released. In March 2008, he agreed to join Brackley Town, a club managed by his one-time Peterborough teammate David Oldfield. Semple left Brackley at the end of the 2007–08 season and spent most of the summer of 2008 without a club. In July 2008, he spent a brief period on trial at Boston United but was not offered a deal. Semple joined Deeping Rangers days before the start of the 2008–2009 campaign, scoring on his debut as Deeping defeated Rothwell Corinthians 5–0 on 9 August 2008. He enjoyed a rich scoring season with the club, the highlight being a five-goal haul against Sleaford Town on 23 September 2008. In April 2009 he signed dual forms with Haverhill Rovers to help them in their quest to avoid relegation from the Ridgeons LeaguePremier Division; Semple works with their manager Peter Betts. On 5 June 2009, Semple joined Gainsborough Trinity. On 4 March 2010, he moved to Boston United. On 29 April 2012, just after two years at the club he was released by manager Jason Lee along with several other players and joined Corby Town. In June 2013 he joined Bury Town. In January 2014 he rejoined Boston United.
