Ishikawa, 20, has 10 wins -- nine on the Japan Golf Tour -- over just three professional seasons but he hadn't qualified for the Masters so he needed a special invitation to compete at Augusta.
"Historically, the Masters has invited international players not otherwise qualified to expand the tournament's global reach," said Augusta National Golf Club Chairman Billy Payne said.
"Ryo Ishikawa is an accomplished player on the Japan Golf Tour and we believe his presence will help increase interest not only in his home country but also throughout Asia."
Ishikawa has played the Masters three times, with a tie for 20th last year his best results.
A player must have a PGA Tour victory or be in the Top 50 of the world golf rankings the week prior to the Masters to earn a regular invitation to the Masters.
The 2012 Masters is to be played April 5-8.