Educated at Tunbridge Wells Grammar School for Boys, he signed a two-year scholarship deal with Gillingham commencing from the 2003–04 season. On 3 August 2004 he missed out on a substitute appearance in a friendly against Thamesmead Town after being stung by a wasp as he retrieved the ball from a tree. In May 2005 his scholarship was extended into a third year and on 22 November 2005 he joined Welling United on a one-month loan deal.

In May 2006 he signed his first professional contract, agreeing to a one-year deal with the club. He made his debut as a second-half substitute for Ian Cox in the 1–0 home defeat to Nottingham Forest on 14 October 2006 and got his first start in the Football League Trophy first leg home defeat to Nottingham Forest. It was announced on 3 November 2006 that he had joined Folkestone Invicta on a month’s loan. He was released by Gillingham in May 2007.

The next season, Howell starts his season as he suffered a knocks and continued to be in and out of the first team through injury and just made 18 appearances, mainly in the second half of the season. He scored his first goal for MK Dons against Hereford United in the 1–0 victory on the final game of the season. He also played twice in the 2009 League One Playoff semi-finals against Scunthorpe United, where he was taken off in the 2nd leg with concussion and was replaced by Alan Navarro in the 17th minutes. In the end of the 2nd leg League One Playoff semi-finals, MK Dons would lose 7–6 on penalties after playing 120 minutes and Scunthorpe United went on to win the play-offs, promoted to the Championship. At the end of the season, Howell, once again, signed a new contract with the club.

Having stayed for the club about two months until on 26 October 2010, he took part in an open training session, while under the supervision of Steve Tilson and Paul Brush at Lincoln City. He is subsequently signed on a one-month loan with the Imps after failing to break into the MK Dons first team. He made his debut, in a 2–2 draw against Wycombe Wanderers. In a match against Morecambe, he suffered a horror tackle from Scott Brown, which he lucky to escape from having a serious injury, which ended his loan spell at Lincoln City. Instead, he was out for four weeks A week later, Howell extended his loan spell until the New Year.

Having made eight appearance, and on 28 January 2011, he had his contract with MK Dons terminated by mutual consent and joined Lincoln until the end of the season. The next day, Howell’s first game after signing for the club on a permanent basis, played when he provided assist for Ashley Grimes, in a 1–0 win over Port Vale. Several weeks later, Howell scored his first goal in a 4–2 loss against Barnet However, a week scoring his first goal, he suffered an hamstring injury, ruling him out for four weeks during a match against Port Vale when he fell awkwardly. Manager Tilson says he doesn’t fear Howell’s injury as serious. Upon recovering from injury, Howell says the team feared relegation.

In May 2011 he was one of just three squad players to be offered a new contract after a mass clear out of players following relegation from the Football League. During his negotiations, he desire refused to rule out to stay at Lincoln City, despite interest from clubs in League One and Two.

On 1 August 2011, Howell signed a deal with Dagenham & Redbridge. Howell previously went on trial with Dagenham & Redbridge, insisting he enjoyed his time in the pre-season friendly. He made his debut, on the opening game of the season, in a 1–0 win over Macclesfield Town. Having played six games, Howell soon suffered an knee injury against Hereford United, which kept him out for a long time. In March 2012, Howell made his return from injury in a 1–0 loss against Northampton Town and revealed his spend 12 weeks in leg brace. During his time spent on the sidelines, the club started a losing, which placed the club into the relegation zone.

The next season, his season changed, having improved dramatically, when he scored nine goals, including a brace against Rotherham United. In January 2013, Howell signed a new contract with the club, which will keep him until 2015.

In May 2016, he re-signed for Dagenham & Redbridge after their relegation to the National League along with Scott Doe on a free transfer, re-uniting with former manager John Still. On 25 May 2018 it was announced that he would leave the club at the end of the season due to the expiration of his contract.

On 2 July 2018, Howell agreed to join fellow National League side Aldershot Town, following his release from Dagenham.

Howell agreed to signed for National League South side Hemel Hempstead Town F.C. on 12 June 2019.