Third-seeded Bautista Agut saved five of the six break points he faced and converted three of his six chances to win in 1 hour, 42 minutes.
World No. 48 Rosol fired 13 aces to Bautista Agut's two, but the Czech was unable to prevent the 23rd-ranked Spaniard from claiming his second title in as many months.
"Since the start of the season, I believed a lot in myself and my work," Bautista Agut told the ATP website. "I've been playing really well, won a lot of matches and it was only a question of time before this happened."
Bautista Agut, who defeated defending champion and top-seeded Fabio Fognini on Saturday, claimed his maiden victory at 's-Hertogenbosch last month.
Rosol, who knocked out second-seeded Mikhail Youzhny of Russia in his semifinal, was also bidding for his second title after winning at Bucharest last year.
"I was looking to find a good rhythm, but the serve was not working at all," Rosol said. "I had to risk a lot with my shots. The level was not as good as the previous rounds and it's a pity because I felt really good this week."