Mannion began playing football at a young age through Aston Villa’s centre of excellence and quickly made a name as a flourishing and versatile defender.
Along with a strong background within football, Mannion also acknowledges that her background within Gaelic football has prepared her physically and mentally for top flight women’s football.
In August 2013, she signed for Birmingham City ahead of the Champions League, where she would make her champion’s league debut against Finnish team PK-35 Vantaa.
At international level Mannion has presented England through Under-15, Under-17 and Under-19 levels, her debut was against Holland in 2010.
She also part of the England squad in the 2010 UEFA European Women’s U17 Championship.