Starting her career at Lincoln, Barker went on to play for the senior side, scoring in the 2008 Women's FA Cup Semi-Final defeat to Arsenal, ahead of moving to Notts County and then Sheffield FC, via a loan spell at Rotherham United.
Doncaster Rovers Belles was her next destination, between 2015 and 2018, named Managers' Player of the Season in 2016. Though Rovers were relegated from the WSL that year, she helped the club win the WSL 2 title in 2017/18.
For two seasons from 2018 until 2020, Barker turned out for Sheffield United in the FA Women's Championship, finishing second in her final season with the Club.
The versatile midfielder made the move to LCFC Women in the summer of 2020 and adorned the skipper's armband for a large section of the 2020/21 campaign - her debut season at the Club, before being made permanent captain.
Barker scored her first Foxes goal direct from a corner in the 9-1 away victory at Coventry United in November 2020 and made a total of 19 league appearances in 2020/21 and 25 across all competitions - playing more minutes than any other outfield player.
Her authority in the middle and tidy playing style has been crucial for the Foxes, allowing them to secure many memorable wins and ultimately lift the Championship trophy at King Power Stadium.
On July 8, 2021, Barker was one of nine players to put pen-to-paper on a new contract ahead of the 2021/22 Barclays FA Women’s Super League campaign, continuing her influence as an experienced head within a relatively young squad.