Hancox was born in Solihull, West Midlands. He has three older brothers; the eldest, Matthew, was seriously wounded in 2011 while serving in Afghanistan with the Royal Marines. Hancox was recruited into Birmingham City's youth system at the age of eight after being noticed playing in a six-a-side competition. As a youngster, he was a Birmingham City supporter, and particularly admired full-backs Jeff Kenna and Martin Grainger and wing-back Stan Lazaridis.
While still a 15-year-old Lyndon School student, he played for Birmingham's reserve team. He was picked out as "one of the bright spots of the evening from a home perspective" in a heavy defeat to Arsenal in the 2009–10 Premier Reserve League, and described by then Academy manager Terry Westley as "one of the few players to come out with any credit" from a defeat to Leamington in the Birmingham Senior Cup. On leaving school, he began a two-year scholarship with Birmingham City in July 2010.
His first competitive involvement with Birmingham City's first team came when he was an unused substitute for the 2011–12 Europa League play-off round second leg against Nacional. Hancox signed his first professional contract, of six months, in May 2012, and was given a first-team squad number in August of that year.
Hancox made his competitive debut in the 1–0 home defeat by Huddersfield Town in the Championship on 6 October, as an 80th-minute substitute for the injured Curtis Davies. He played at left back, allowing Paul Robinson to move to centre back, and according to the Birmingham Mail, "can be pleased with his urgent and determined contribution in the last 10 minutes. He's only on a six-month contract but would sweat blood for his boyhood club." A few days later, he was given a six-month extension to his contract. When Robinson took over from Steven Caldwell as first-choice centre back, Hancox was able to establish himself at left back. He ended the season with 20 appearances, including 14 starts, and signed a new three-year contract.
With David Murphy still recovering from injury, Hancox hoped to establish himself as first choice at left back, but a bruised testicle sustained in training and the loan signing of Shane Ferguson obstructed his progress. His first appearance of the season was in mid-September, as a substitute with Birmingham already 3–0 down at Burnley, followed by two League Cup ties, the second of which, at home to Stoke City, was 4–4 after extra time. Hancox volunteered to take the first penalty in the shootout, but his powerful kick struck the top of the crossbar and went over; Birmingham went on to lose the shootout. A run of games in November was halted by a knee injury, and ankle damage put an end to another run in the new year. He returned for the last few matches of the season, with Birmingham in danger of relegation. Needing at least a point from the final fixture, at Bolton Wanderers and for other results to go in their favour, Hancox came on at half-time, and two minutes after Bolton took a two-goal lead, he crossed for Nikola Žigić to score with a header. Well into stoppage time, Paul Caddis scored the equaliser that kept Birmingham in the second tier.
In the 2014 close season, Lee Clark signed left-back Jonathan Grounds, who was almost ever-present under the management both of Clark and his successor Gary Rowett. Hancox played only one first-team match in 2014–15, in the FA Cup against Blyth Spartans, but he was a member of the 2015 Birmingham Senior Cup-winning team, consisting mainly of reserve-team players but also including first-teamers Matt Green and Žigić,who was making his last appearance for the club.
After just one League Cup appearance in 2015–16, Hancox joined League Two club Crawley Town on a month's loan on 2 October 2015. He went straight into the starting eleven for the next day's visit to Plymouth Argyle, which Crawley lost 2–1 to a very late goal. In his second League Two match, at home to Leyton Orient, he scored his first senior goal. The score was 1–1 when Orient's goalkeeper Alex Cisak put the ball behind from Hancox's cross. Hancox himself took the corner, and when it was cleared he hit the loose ball past Cisak at his near post. He then made the pass that put Rhys Murphy through on goal, Murphy was fouled for a penalty that put Crawley two goals ahead, and the team held on for a 3–2 win. After he started all seven of Crawley's matches during his first month with the club, his loan was extended for a second month, and then a third. He finished his loan spell with two goals from sixteen appearances in all competitions.
Hancox played no more first-team football after returning to Birmingham. His last appearance for the club was as captain of the reserve team in the 2016 Birmingham Senior Cup final defeat to National League North champions Solihull Moors. Anxious for regular football, he was released when his contract expired at the end of the season; he had been with the club for fourteen years, and made 40 first-team appearances without scoring.
Hancox signed for National League club Macclesfield Town on 4 August 2016. He made his debut two days later in the opening match of the season, a 2–1 win against Torquay United, but in his third match, a 3–1 defeat of Braintree Town, he conceded a penalty and was sent off for two yellow cards. In December 2016, Hancox signed a new deal with Macclesfield to run until the end of the 2017–18 season. As well as at left back, he also featured as a holding midfielder for Macclesfield. He finished his first season with 38 National League appearances and 6 goals, which included a hat-trick against Boreham Wood in March 2017, and helped his team reach the 2017 FA Trophy Final against York City. He took the free kick that led to Rhys Browne making the score 1–1, but Macclesfield finished on the losing side.As of match played 9 September 2017
Macclesfield TownFA Trophy runner-up: 2016–17