Nadal was simply red hot in the first set but got lucky in the second when Gonzalez, who stood toe-to-toe with the 22-year-old tyro, fluffed an easy backhand volley on set point.
The ruthless Nadal needed no second invitation and moved in for the kill as Gonzalez began to buckle.
Gonzalez gamely hung on at 2-5 in the third set, saving three match points, but it was only delaying the inevitable and Nadal converted his fourth chance in the next game.
Serena and Venus finish the job
"It's very difficult to win this because you only have one chance every four years," Nadal said afterwards.
"I played almost a perfect match."
Nadal, who will end Roger Federer's four-and-a-half year reign as world number one on Monday, is the first Spaniard to win an Olympic gold in tennis.
The 28-year-old Gonzalez now has the full set of Olympic medals after his doubles victory in Athens four years ago, when he also took bronze in singles.
Who knows what might have happened if, after matching Nadal shot for shot in a superb second set, he had made the volley he missed on set point at 6-5.
"I was expecting the pass on the other side," Gonzalez said. "I'm a bit sad, when you get to the final you want the best [medal].
Serbia's Novak Djokovic completed the podium after beating American James Blake in the bronze medal match.
Factbox - Rafael Nadal
Age: 22 (date of birth: June 3, 1986)
Place of birth: Manacor, Spain
Four French Open championships (2005, 2006, 2007 and 2008)
One Wimbledon championship (2008)
Previous Olympic result:
First round, 2004 Olympics, men's doubles
Nadal set a record of 81 unbeaten clay court matches from
April 2005 to May 2007, breaking the previous mark of 53 matches set by Guillermo Vilas in 1977.
He became the first player since Bjorn Borg (1978 to 1981) to claim four successive French Open titles, having won his 28 matches on the Paris clay since his debut in 2005.
His uncle Miguel Angel Nadal was a professional footballer and played for Barcelona, Real Mallorca and also represented Spain in three World Cups.
Nadal's hobbies include football, golf, fishing, computer games and watching movies.
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