He played as a central midfielder for English club sides Nottingham Forest, Newcastle United, Tottenham Hotspur, Aston Villa and Queens Park Rangers, scoring a career total of 39 goals from 341 league appearances. He also appeared 21 times for the senior England national football team, scoring one goal.
A promising talent, Jermaine Jenas made his professional debut at age 17 for his boyhood club Nottingham Forest who were playing in the second tier, before moving to Premier League club Newcastle United for £5 million just over a year later, where he earned his first senior England cap in February 2003 aged 19 and was named PFA Young Player of the Year for the 2002–03 season. Hampered by several serious injuries, Jenas failed to reach the career heights expected of him, although he remained at the top level, moving to Tottenham in 2005 for £7 million, with whom he won the Football League Cup in the 2007–08 season. While with Tottenham, he travelled with England to the 2006 FIFA World Cup but was an unused substitute; he played his last England match in 2009.
The tail end of his playing career saw loan spells at Aston Villa in the Premier League in 2011 and Nottingham Forest in the second tier in 2012, before a permanent move to struggling Premier League club Queens Park Rangers in the January 2013 transfer window. Relegated with QPR in May, he played for much of the following season before injury finally forced his retirement.
After Jermaine Jenas was released by QPR, he moved into television as a freelance pundit, firstly he was an analyst for ITV Sport's coverage of the 2014–15 UEFA Europa League. In November 2014, he joined BT Sport where he regularly features in the studio alongside other pundits to provide analysis on the game.
In 2015, Jermaine Jenas appeared as part of Channel 4's Time Crashers, a reality television programme in which celebrities were assigned the tasks of living in different historical eras.
Jermaine Jenas presented a BBC Three documentary in April 2017 on knife-crime, focusing on his home town of Nottingham. During Teenage Knife Wars, he recalled an incident in his youth where he was the victim of a knife-point robbery.
In 2020, Jenas began co-presenting The One Show on BBC One with Alex Jones. In 2021 Jenas became one of its permanent hosts.
On 1 April 2022 Jenas was the "Draw Conductor" for the 2022 FIFA World Cup draw.