Millwall Bostwick began his career as a trainee at
Millwall, playing regularly in the club's under-18 and reserve teams. In the latter stages of the
2005–06 season, Bostwick joined
Conference National club
Crawley Town on a work experience
loan, making his debut as an 89th-minute
substitute in a 1–0 win against
Forest Green Rovers on 18 March 2006. He made his first start on 15 April 2006, scoring in a 2–0 victory over
Aldershot Town, and finished the spell with eight appearances and three goals. He returned to Millwall in May 2006 and signed a one-year professional contract. Shortly before the
2006–07 season, Bostwick returned to Crawley on loan. He played in the first five matches, scoring twice from midfield in a 3–2 win at
Stevenage Borough on 18 August 2006. The loan was extended until the end of the season, with Millwall retaining the option to recall him. Bostwick made 25 appearances and scored twice before being recalled by Millwall in January 2007.
Rushden & Diamonds Having made no first-team appearances for Millwall, Bostwick joined Conference National club
Rushden & Diamonds on an 18-month contract. Managed by
Graham Westley, who had previously written about Bostwick's credentials in his weekly column in
The Non-League Paper, he made his debut in a 2–1 away victory at league leaders
Dagenham & Redbridge on 10 February 2007. Bostwick was
sent off for the first time in his career in a 2–2 draw with Aldershot Town on 24 March 2007, following two bookable offences. He made eight appearances for Rushden before falling out of favour following Westley's departure in February 2007 and was released by the club at the end of the season. Signed to provide depth and cover in defence and midfield, He scored his first goal in a 1–1 draw with
Exeter City on 22 September 2007. Bostwick signed a contract extension on 23 November 2007, keeping him at the club until the end of the season. He made seven appearances in Ebbsfleet's
FA Trophy run that season, scoring in a 1–1 draw against Aldershot Town in the semi-final second leg on 15 March 2008 and played the full match in the 1–0
final victory over
Torquay United at
Wembley Stadium on 10 May 2008. Across all competitions, he made 51 appearances and scored five goals during the season. He made his debut in the club's opening match of the season, a 5–0 defeat to
Wrexham at the
Racecourse Ground on 9 August 2008. He also scored in a 1–0 away victory at
Chester City on 19 September 2009, although the result and goal were later expunged following Chester's expulsion from the league. Bostwick featured in the 2–0 victory against
Kidderminster Harriers on 17 April 2010 that secured Stevenage's promotion to the Football League for the first time in the club's history. He made five appearances in the club's FA Trophy run, Bostwick made 52 appearances in all competitions that season, scoring eight goals. but Bostwick signed a new two-year deal on 10 June 2010 amid interest from several
League One clubs. He made his Football League debut in Stevenage's opening match of the
2010–11 season, a 2–2 draw with
Macclesfield Town on 7 August 2010. He scored his first goal of the season in the club's first Football League victory on 21 August 2010, a 3–1 win against
Stockport County, doubling the lead with a 30-yard strike. Bostwick made 51 appearances in all competitions, scoring three goals, including three appearances in the
League Two play-offs. Stevenage secured
promotion to League One with a 1–0 win over Torquay United at
Old Trafford on 28 May 2011, in which Bostwick played the full match. He signed a two-year contract extension on 26 August 2011, and scored eight goals from midfield in 53 appearances during the
2011–12 season Over four seasons with the club, Bostwick made 206 appearances in all competitions, scoring 21 goals. Chairman
Darragh MacAnthony stated he was manager
Darren Ferguson's "number one transfer target for the summer". He made his Peterborough debut in a 4–0 home victory against
Southend United in the League Cup on 14 August 2012, and scored his first goal in a 2–1 home defeat to
Leeds United on 25 August 2012. Appointed
captain ahead of a home match against
Derby County on 27 October 2012, he opened the scoring with a volley in a 3–0 victory. Bostwick made 42 appearances in his
first season, scoring five goals, as Peterborough were relegated from the Championship. In the
2013–14 season, he moved from central midfield to a regular role at centre-back, turning down a higher offer from
Blackburn Rovers as he did not want to relocate to the north of England. Deployed regularly at centre-back under manager
Danny Cowley, he made 49 appearances as Lincoln won the League Two title and promotion to League One.{{cite news
Burton Albion Bostwick signed for League One club
Burton Albion on 5 August 2020, on a one-year contract,{{cite news
Return to Stevenage Having made 10 appearances for Burton throughout the first half of the
2021–22 season, during which he sustained a hamstring injury,{{cite news
Boston United Bostwick joined
National League North club
Boston United on 6 June 2023.{{cite news
St Albans City Bostwick joined
Isthmian League Premier Division club
St Albans City on 5 June 2025, reuniting with manager Ian Culverhouse, who had previously signed him for Boston United. Following Culverhouse's departure, Bostwick was appointed player-interim manager on 29 October 2025.{{cite news ==International career==