Andre Williams and Clarence Paul wrote it in Detroit around 1962 while working for Motown in the early days.
The word "Mojo" traveled from Africa to North America with the slaves and survived in the voodoo cult, that means basically in the New Orleans area, where, after all, also the cradle of the Blues was located.
Then it occurred in Muddy Waters' Song "Got My Mojo Working". And since he was known for showing off with his potency, like in "Mannish Boy", everybody took it from him as a sexual allusion. But if you have a close look at the complete lyrics of "Got My Mojo Working", it might as well be interpreted as male attractiveness, charme ect. And then the word is to be found in other songs like in "Mojo Hannah" by Williams and Paul. I know this one done by the Neville Brothers, and there "Mojo" means "magic" and "voodoo" again.
