Saville is a left-sided central defender who joined Southampton from Chelsea's youth system in March 2009 after four years at Chelsea. He joined Chelsea's academy from Reading Under-14's and played over 20 games in Chelsea's 2007–08 youth side before being promoted into their reserve team squad. Saville turned professional in time for the 2009–10 season, penning a three-year contract with Southampton on 1 July 2009. As a result of being promoted to the club's first team, Saville was given number thirty-seven shirt. Saville then joined Stockport County on a month loan on 4 November 2010. On 11 August 2011, Saville joined Hayes & Yeading United on a three-month loan. His performance led Manager Nas Bashir impressed with his performance, quoting: "He did well when he came on and we are creating a good squad here with competition for places. The boys are aware that they keep the shirt if they play well, but if they do not then someone will come in and take their place." However, his loan spell with Hayes & Yeading United was soon cut and returned to his parent club.
On 7 November 2011, Saville joined Barnet on loan for a month and made his first appearance for Barnet on 12 November 2011 coming on from the substitutes bench during an FA Cup match against Southport. On 2 February, Southampton terminated Saville's contract enabling him to join Barnet on a permanent basis. Crewe made a loan bid to sign Saville before he joined Barnet. Saville's first game after signing for the club on a permanent basis came in a 1–0 loss against Swindon Town in the Southern Section of Football League Trophy. Saville made seventeen appearance for Barnet, to help the club survive relegation in The Football League for another season. At the start of the 2012–13 season, Saville was included in the first five matches and scored his first goal for the Bees in a 3–1 defeat at home to Gillingham. However, only eight starts to the season led Saville joined Ebbsfleet United on a month's loan on 11 January 2013., which was later extended until the end of the season. The 2013–14 season saw Saville make a return to the first team at Barnet for two matches before being in the bench for twelve matches, as well as, his own injury concern. Saville had featured in the first team from 5 October 2013 to 18 February 2014 before suffering a hip injury. Saville was able to make his return weeks later on 8 March 2014, in a 1–0 loss against Gateshead. Saville went on to make twenty-three appearance for the club. At the end of the season, it was announced that Saville was being released, though he was invited back to the club for pre-season training. However, he was later offered a new one-year deal, and it was announced he would be staying with the Bees on 2 June 2014. The 2014–15 season saw Saville featured for four matches at the start of the season before being absent between 10 September 2014 and 4 October 2014, due to ankle injury he sustained against Alfreton Town and made his return against Macclesfield Town, which Barnet lost 2–1. Throughout the 2014–15 season, Saville would be often used in first team ins and out, at either centre-back or left-back, which saw him made twenty-six appearance for the club. Following the club's promotion back to League Two, Saville was released at the end of the season,
Saville is the older brother of fellow Chelsea youth product George Saville who represent Northern Ireland internationally. Jack, like his brother George, is eligible to play for Northern Ireland as his grandmother was from Enniskillen
