The 24-year-old Japanese driver finished second behind Vittorio Ghirelli in the 2013 Auto GP series.
He drove for the Sauber Formula 1 team during the young driver test at Silverstone last July.
Sato will complete Campos's driver line-up in GP2, joining Arthur Pic, who was confirmed at the Spanish squad last month.
"I'm very happy to be joining Campos Racing and to be entering the GP2 championship with them this season," said Sato, who is yet to drive GP2 machinery.
"GP2 was always the logical next step for me after finishing second in the Auto GP championship last year and I am very pleased that we have been able to reach an agreement with a top team like Campos."
Campos returns to GP2 after taking the place of the Addax squad.
"I am delighted to have Kimiya with us this season," said team boss Adrian Campos. "I do believe he will make a leap forward in quality, despite having an excellent record in previous categories.
"Without any shadow of a doubt we will do a great job with him."
Pre-season testing kicks off on March 11 in Abu Dhabi.
- Sports & Recreation
- Campos Racing