Davis was born in Burnley, Lancashire. After progressing through the club's academy, he made his first-team debut for Crewe Alexandra on 8 May 2010, in a 1–0 defeat to Bradford City on the final day of the 2009–10 season. Before making his Crewe debut he enjoyed a short loan spell at Northern Premier League Premier Division team Nantwich Town. He was given his first professional contract in May 2010. In August 2010 he joined Stafford Rangers of the Conference North on a one-month loan, along with teammate Kelvin Mellor. His second game for the club came on the final day of the following season, also against Bradford. Crewe won the game 5–1 at Valley Parade. He started in the first game of the following season, a 3–0 defeat away to Swindon Town. He began to feature regularly under manager Dario Gradi and scored his first goal for the club in a 3–1 defeat to Southend United on 8 October 2011. A few games later he scored in a 1–0 away win to Cheltenham Town. On 10 November 2011, Gradi stepped down as manager of Crewe, with Harry's father Steve Davis taking over as manager. After scoring penalties in a 1–0 win against Bradford, a 3–0 win against Bristol Rovers and in a 1–1 draw against Rotherham United, Davis helped Crewe to reach the 2012 League Two play-off Final at Wembley Stadium, which Crewe won 2–0 against Cheltenham and were promoted to League One. In January 2015, Davis signed a -year contract to remain at Crewe. He was announced as club captain for the 2015–16 season. At the end of this contract, Crewe announced that Davis had been released by the club.
St Mirren
On 31 January 2017, Davis signed on loan with Scottish Championship side St Mirren until the end of the 2016–17 season, and scored on his debut in a 2–2 draw at Dumbarton. Davis suffered a knee injury in St Mirren's 3–2 win over Dundee United in the Scottish Championship on 15 March 2017, after scoring his third goal for the club, and was set to return to Crewe for treatment. He signed on a permanent basis with St Mirren on 1 August 2017. Davis helped St Mirren win the 2017–18 Scottish Championship, but decided to leave at the end of the season for family reasons.
Throughout his career, Davis is noted as a centre back and can also play as a right back, he established himself as a full back at Crewe in the 2011–12 season under Dario Gradi.
Personal life
Harry Davis's playing career at Crewe coincided with his father, Steve's managerial roles at the club. Steve Davis was assistant manager at Crewe as Harry made his debut, later becoming manager. When Steve Davis was sacked in January 2017, Harry Davis sought a loan move away from the club. Harry's younger brother, Joe, is a defender at Port Vale, having previously been at Port Vale, Leicester City and Fleetwood Town. On 22 February 2014, for 33 minutes of a match at Port Vale, the two brothers played on opposite sides against each other.
