The winner of the 2009 Vuelta a Espana took the victory ahead of Team Sky's Sergio Henao at the end of a 153km trek from Deia to Monasterio de Lluc.
The route on the south-west coast of Mallorca saw two third-category climbs, two second-category climbs and an ascent of the first-category Coll de Puig Major.
There was a string of attacks on the Puig Major with Valverde and Movistar team-mate Rui Costa plus Henao and Blanco's Dutch climber Robert Gesink making the decisive move.
They crossed the summit, which came 19km from the finish line, ahead of the whittled down peloton and held off the chasers on the run-in to the finish where Valverde - a winner of four stages in the Tour de France - showed his speed on the uphill drag to the line.
Team Sky's Ben Swift led the bunch home in fifth, 51 seconds behind the winner.
Valverde said: "I knew I was strong, but I didn't quite know how my reactions were going to be as I'm taking things more cautiously this season.
"I knew I had ended the 2012 season in really good shape, and came here with good motivation, and it's true that once you're up-front, you always try to win.
"When on the climb it was just me and Rui with Henao and Gesink, it was a matter of attacking by the two of us to drop Henao, but he was really strong and responded well, so we waited for the sprint.
"Taking a victory so early in the season is always better, because it gives confidence to you as well as to the squad."
Challenge Mallorca sees teams able to enter squads of 10 riders and rotate their line-up through the four days.
- Sports & Recreation
- Sergio Henao
- Robert Gesink
- Team Sky
- Rui Costa