It will if it uses what Ruger calls "AI" style magazines. If you have a Ruger American Predator model that uses rotary magazines it will not work.
I bought the Ruger American Predator a few weeks ago, and just picked up four of these five round magazines. They do not fully seat with the bolt closed, and when open, not until slapped hard. Then the bolt will not close. PMAG AC is a great product, but I don’t know if Ruger did their homework before releasing this.