Hard-working, tenacious, attacking midfielder Shelvey was one of Rafa Benítez’ last signings at Liverpool. When Shelvey was only 16 years and 59 days old he became Charlton Athletic's youngest-ever player when featuring for the Addicks against Barnsley in the Championship on 26 April 2008. A year later Chelsea came calling but by rejecting the London Blues, the young East Londoner had obviously thought carefully about a career path that would give him the best chance of success. He stayed loyal to the first club that had offered him a professional contract, Charlton Athletic. Shelvey made 49 appearances for the London club, scoring eight goals before accepting a move to Liverpool two years later. The Reds paid an initial £1.7m with further potential payments up to £3m depending on domestic and international appearances.

If it was unsettling that Rafa, who had signed him, left so soon after his own arrival at Anfield, it soon became clear that incoming boss Roy Hodgson was already aware of the midfielder’s promise. Still a teenager when his debut season as a Liverpool player finished, Shelvey could look back on 21 first-team appearances, but he only made four starts. Shelvey joined Championship side Blackpool on loan at the end of September until 31 December 2011, but returned home a month earlier the day after Lucas Leiva was stretchered off in Liverpool's League Cup quarter-final at Stamford Bridge. Shelvey had tremendous success at Blackpool, scoring six goals in ten Championship matches, including a hat-trick in a 5-0 victory at Leeds. Shelvey made nine starts in 2011/12 and could be pretty happy with his progress although he didn't feature in either cup final. The run of matches he had in the second half of the season must have done wonders for his confidence. In the final home match of the season, he scored his first Premier League goal with a blistering shot from distance that flew past Chelsea goalkeeper Ross Turnbull like a guided missile. In the second week of July 2012 Jonjo signed a new long-term contract. "Tactically I have become a lot better and technically too," Shelvey said. "When you're working with people like Steven Gerrard and people like that, you're learning things day in, day out and it's an honour."

Shelvey had an impressive start to 2012/13, which included three goals in two Europa League matches, scoring home and away against Young Boys of Bern and also opening the scoring in the home defeat by Udinese. Shelvey earned a call-up to England's senior squad for the first time for the October World Cup qualifying matches against San Marino and Poland. He made his full international debut when coming on as a second-half substitute for Michael Carrick in the first of those two matches, against the group minnows at Wembley. Shelvey appeared in just under 60% of Liverpool's competitive matches in 2012/13, a season in which he celebrated his 21st birthday. But he only started three matches in the second half of the season and was an unused substitute almost as many times as he actually played from the start. Shelvey did lack composure and concentration when involved in the heat of battle in midfield. Rodgers felt he did not use the opportunities given and he was sold to Swansea in the summer of 2013. He became an integral part of their midfield and in September 2015 was called up to the England squad for the first time in three years. Shelvey was sold to Newcastle United in January 2016 for £12m of which Liverpool earned 10% of Swansea's £6m that they made on their sale. Shelvey was named captain on four occasions but he couldnt help Newcastle avoid the drop.

Despite relegation Shelvey remained with Newcastle for 2016/17. Apart from four games out suspended, he was an ever present and scored five times as they made an instant return to the top flight. 2017/18 saw him appear thirty times, scoring once. 2018/19 was a frustrating season in Tyneside for Shelvey, who struggled to force his way back into the side after picking up a thigh injury in November. He made only sixteen appearances in the league all season and in April 2019 was forced to deny rumours of a rift with manager Rafa Benitez, saying he had to accept others had seized their opportunity in his absence. In 2019/20, with Steve Bruce now manager, Shelvey featured more often and scored five times in 25 starts, nine of which he was captain. He stood in as captain on occasions again in 2020/21 when he started 29 times.