Yashere was born in Finsbury Park, London, England. Before becoming a comedian, she worked as a lift maintenance engineer. Her mother emigrated from Nigeria.
Yashere was a finalist in the prestigious Hackney Empire New Act of the Year competition in 1996. She continues to actively perform live stand-up comedy to the present, appearing on such shows as Mock The Week.
She has released two live stand-up DVDs: one in 2006, and one in 2008.
She has appeared in many television programmes, but is probably best known for appearing in the comedy series Lenny Henry in Pieces as well as voicing Keisha on Bromwell High.
In 2005, she appeared in the reality television series, Comic Relief does Fame Academy, in aid of Comic Relief, and she co-hosted the 2006 MOBO Awards alongside Coolio. She has also appeared on Mock the Week and a show on CBBC called Gina's Laughing Gear.
In 2007, she tried out for Last Comic Standing during the Sydney, Australia auditions. She qualified for the semi-finals and was then chosen as one of the ten finalists to compete in the final rounds of Last Comic Standing. On August 1, 2007, in the first elimination round, she was eliminated along with Dante.
In 2008, she was the first-ever British person to be on Def Comedy Jam.