Sumaila joined from LA Orange County from Storm FC, where she played with compatriot Jennifer Cudjoe, who joined Ashville City FC.
The sleek poacher took to Twitter to state her readiness for the challenge ahead," LA Galaxy OC here I come."
Los Angeles Galaxy Orange County is the female side of Major League Soccer club LA Galaxy.
The 23-year-old striker was part of the famous Black Maidens team that won Bronze in Azerbaijan in 2012 and was a member of the Black Princesses team that participated at the FIFA U-20 Women World Cup in Cananda.
She is yet to feature for the senior national female team, the Black Princesses.