Nadal complained of fatigue coming into the series but showed no symptoms as he dominated the 10th-ranked Frenchman on the outdoor clay at Cordoba's bullring to give the hosts a chance at a third title in four years. Spain won 4-1 after Fernando Verdasco beat Richard Gasquet 6-2, 6-1 in the final reverse singles.
Tsonga replaced Gilles Simon for the reverse singles match after an impressive doubles victory but was frustrated by 50 unforced errors.
"Simply put, Rafa was just too good this weekend," Tsonga said. "He's the best player ever on clay court, I think, he's practically unbeatable on this surface and today we didn't create the exception."
Tsonga's erratic play against a player who has won 32 titles on clay left little doubt over the result as Nadal served out the victory in 2 hours, 17 minutes when Tsonga shot wide.
Nadal, who never faced a break point, improved to 14-0 on clay and 18-1 in Davis Cup singles play. Nadal was a member of three of Spain's four title-winning teams and leads it into its sixth final since 2000 and eighth overall.
"You might think it gets easier to win but it doesn't," Nadal said after allowing Tsonga just six points on his serve. "Thanks to the excellent relations inside the team, the Spanish players have stayed united over the years to keep winning."
Nadal has complained about the overcrowded tennis calendar sapping his stamina as he raced from his U.S. Open final defeat to Djokovic in New York on Monday to rout Gasquet on Friday. But on Sunday, Nadal was energized and had only eight unforced errors.
"He had a tough time keeping the ball in," said Nadal, whose lone Davis Cup defeat came in his debut in 2004. "It was tough to play in this heat."
Tsonga started with an ace but Nadal closed that first game with the first of six break points to ignite the boisterous crowd, which launched into chants of "Torero" (Bullfighter) throughout the afternoon at the Los Califas bullring.
Nadal clinched three break points in the first set after Tsonga sent a backhand into the net, double-faulted and finally sent a backhand wide.
Tsonga switched to serve-and-volley with some success as both players held serve to start the second set until Tsonga hit a forehand long while facing a triple-break point in the fifth game. Nadal was ahead and broke again in the seventh game when his opponent sent another backhand wide.
"He pushes you to make mistakes. It looks like I'm making errors, but he's the one pushing you to make those," the Frenchman said. "It's really hard to return his shot. It's less the surface than how Rafa hits his shot."
The six-time French Open champion closed out the set by hitting a forehand down the line for one of 21 winners on the afternoon.
Tsonga managed to hold until the seventh game of the final set when he raced forward to smash into the net to give Nadal a double-break opportunity. The second-ranked Spaniard converted his final break when the Frenchman volleyed his backhand wide.
The final will take place in Spain with Valencia and Madrid reportedly interested in hosting the event.
Roger Federer's Switzerland clinched its spot in the World Group after Stanislas Wawrinka needed only four minutes Monday to complete a 4-6, 6-4, 6-7 (7), 6-4, 6-3 win over Australia's Lleyton Hewitt.
Wawrinka led 5-3 in the fifth set Sunday when darkness suspended the match after 3 hours, 58 minutes.
On Sunday, Federer defeated Bernard Tomic 6-2, 7-5, 3-6, 6-3 to pull Switzerland level at 2-2 after Australia won Saturday's doubles and the teams split the opening singles on Friday.
Australia, which has won the Davis Cup 23 times, second only to the United States' 32 titles, will spend a fifth year out of the top competition.
Information from The Associated Press was used in this report.