Andujar broke the fifth-seeded Starace's serve twice in each set and saved the only two break points he faced, continuing the form he displayed in knocking out top-seeded Albert Montanes in the semifinals.
"I was very confident before the match," Andujar said. "I thought about winning and yesterday's win gave me a lot of confidence. I played in a way that made him tired, being very aggressive and making him run a lot."
The 25-year-old Andujar lost his only previous final, last year at Bucharest, also on outdoor clay.
"I didn't expect this title and it comes as a surprise for me," Andujar said. "The conditions are close to the ones in Europe and it's only a two-hour flight from Valencia. This is a very good tournament to start the clay season."
The 29-year-old Starace, who had a grueling semifinal Saturday against No. 8 Victor Hanescu of Romania that went to a tiebreaker in the third set, has now lost all four career finals.
Those final losses came last year at Umag, Croatia, and at Kitzbuhel, Austria, and Valencia, Spain, in 2007.
Starace admitted he was totally outplayed.
"He was too aggressive and didn't give me one chance, so congratulations to him," Starace said. "He was playing a very high level."