Third-seeded Sonego had to dig deep in the second set before prevailing 2-6, 7-6 (5), 6-4 in a final lasting just over three hours.
“The match was long and I remained calm in the second-set tiebreaker,” Sonego said. “I knew the match wasn’t finished because I had always kept fighting.
“Now, I am really tired, but I am very happy. I am happy to follow in [Filippo] Volandri’s footsteps and win a title on home soil.”
It was Sonego’s second trophy in as many days after he partnered Andrea Vavassori to the Cagliari doubles title on Saturday, and his second singles trophy overall.
Djere, who won the first edition of the tournament at Forte Village in October, got off to the best possible start as he broke serve in the first game. He went on to save three break points in his first service game and broke again with a superb backhand winner for a 5-2 advantage, before wrapping up the set.
The 25-year-old Sonego recovered to take a 4-1 lead in the second set but Djere struck back to win three straight games. However, Sonego clinched the tiebreaker with a forehand volley.