The Nationals and the right-hander agreed Wednesday to a minor league contract, and he will compete during spring training for a spot in the rotation. If added to the 40-man roster, he would get a $900,000, one-year contract and the chance to earn $1.25 million in performance bonuses.
The 35-year-old Hernandez went to spring training with the New York Mets last year on a minor league deal and won a spot in their rotation, going 7-8 with a 5.47 ERA in 23 starts before being released Aug. 20.
The Nationals signed him six days later and Hernandez went 2-4 with a 5.36 ERA in eight starts, posting six quality starts.
Hernandez was Washington's opening day starter in 2005 and 2006. He was MVP of the 1997 World Series with the Florida Marlins.