She raised herself among the fastest ever over 5000 m indoors with a run at the 2009 Boston Indoor Games, just nipping ahead of Shalane Flanagan at the line to win in 14:47.62 minutes.
Mrisho was selected as one of three representative for Africa in the women's 5000 m at the 2010 IAAF Continental Cup (along with Vivian Cheruiyot and Sentayehu Ejigu and she finished in fifth place.She won the adidas Women's 5K in Prague in September 2010, beating runner-up and defending champion Gladys Otero by a margin of seventeen seconds.