Liam Manning was part of the Norwich City academy setup until the age of 14/15 when he played alongside the like of Lee Catchpole. The versatile defender / midfielder had also played youth football for Bungay Town and captained Suffolk. He was spotted by Ipswich scout Adrian Hunt at the age of 14 and eventually switched to the Portman Road academy, where he has progressed through the youth teams and has played for Ipswich's reserves.

Released by Ipswich in the spring of 2005, he trialled for Dagenham & Redbridge in July 2005, playing against Brentford. Instead, he signed for Conference South side Bishops Stortford. He later joined Ridgeons League side Long Melford but was soon released and joined their rivals Leiston. In November 2005, he switched again, joining Woodbridge.

Liam moved to Wroxham in October 2008

Having decided to turn his hand to coaching following the end of his playing career, Manning returned to Ipswich, where he spent nine years honing his craft before making the move to east London in 2015 to join West Ham as Assistant Academy Manager. He was later West Ham's Head of Coaching and Under-23s overseeing the development of Grady Diangana and Declan Rice during his four years in the capital.

In April 2019, Manning joined the City Football Group and was named Director of Coaching for the New York City Academy although he was quickly promoted to Academy Director. During his short time in the US, Manning led NYCFC to a second consecutive U.S. Soccer Development Academy Under-19 National Championship. In 2020 Manning was appointed Head Coach of Belgian second division side Lommel SK, where he was tasked with rebuilding a team who had won just six games during the 2019/20 season. As well as implementing a new style of play, he also guided them to a third-place finish, one spot shy of a promotion play-off place.

On 13th August 2021 he was appointed as Head Coach of MK Dons replacing Russell Martin.

Manning guided the Dons to a third-place finish and the League One play-offs in 2021/22 but they missed out on the chance of promotion after losing to Wycombe Wanderers over two legs.The squad had to be rebuilt following a number of subsequent departures and they lost their first three league games of the 2022/23 season without scoring a goal. Two wins in the next three pushed them up to 13th in the table by the end of August but they were in the relegation places since a 2-1 defeat at Shrewsbury on 8 October. He was sacked by the Dons on 11th Deeember 2022.

On 11th March 2023, he was appointed as the new manager of Oxford United, taking over from Karl Robinson who was sacked in February following an eight match winless run. Chairman Grant Ferguson said  "Liam has a fantastic reputation as a coach and for helping to develop young players. His sides play with a sense of identity and purpose and play attacking football and that is something that Oxford United have always tried to do.We had an outstanding list of candidates and as promised we went through a rigorous recruitment process but Liam was our unanimous choice."

On 7th November 2023 he left Oxford to become Bristol City's new manager replacing Nigel Pearson who was sacked in October 2023 after a run of five losses in seven games.Manning left Oxford in second place in League One. "This is a terrific opportunity and one that I'm really looking forward to," said Manning, who has signed a three-and-a-half-year contract at Ashton Gate. "If you look at the vision of the club and where they want to get to and how they want to get there I think there is really good fit and alignment with my journey and where I want to get to."