The deal, announced by Washington on Sunday, includes a $500,000
signing bonus and salaries of $3.25 million in 2012, $6.25 million
in 2013, $8.5 million in 2014, $11 million in 2015 and $12 million
Gonzalez, 26, was traded from the Oakland Athletics in December for four minor league prospects.
"Gio's ample talents are well known and chronicled," Nationals general manager Mike Rizzo said through a team spokesman. "Today's extension was about comfort for both parties. From our end, the two option years and team control were imperative to the extended commitment.
"Now both Gio and our fans can shift their focus and excitement to his debut in DC knowing that their relationship won't be ending in the short term."
Gonzalez went 31-21, with an 3.20 ERA and 368 strikeouts in 402 2/3 innings over the last two seasons.
Gonzalez earned his first All-Star Game nod in 2011 when he was 16-12 with a 3.12 ERA in 2011.
The lefty was eligible for salary arbitration for the first time in his career.
Catcher Jesus Flores, who also was eligible for arbitration, agreed Monday to an $815,000, one-year contract, a raise of $65,000.
The 27-year-old hit .209 in 86 at-bats last year after missing the 2010 season following surgery to repair a torn labrum in his right shoulder. He was hit by a foul ball on May 9, 2009, returned for three at-bats that September and then had the operation.
Information from ESPNDeportesLosAngeles.com's Enrique Rojas and The Associated Press was used in this report.