The Finn earned the decisive break to go up 6-5 in the third set when Bellucci's forehand sailed long. Nieminen then held his serve to close out the match.
"I didn't believe he could serve so well,'' Nieminen said. "He also played well otherwise. I was somewhat passive in the beginning. Then I played more aggressive. I kept thinking positive and fought until the end.''
The 33rd-ranked Nieminen is making his ninth straight appearance in the Royal Tennis Hall. He reached the 2001 final, losing in five sets, and made the quarterfinals last year.
Bellucci, a 20-year-old Brazilian, made his ATP main draw debut in February and is ranked 80th.
In another first-round match between two qualifiers, George Bastl of Switzerland outlasted Frederik Nielsen of Denmark 7-6 (6), 3-6, 7-6 (4).
Also, Arnaud Clement of France routed Swedish qualifier Bjorn Rehnquist 6-2, 6-1.
Roger Federer withdrew from the tournament last week, leaving seventh-ranked David Nalbandian as the top-seeded player.
Defending champion Ivo Karlovic skipped the tournament, held for the 40th time.
Bjorkman plays 1,000th ATP doubles match
Federer withdraws from Stockholm Open
Maniche Suffers Back Injury
