Rolfo made his first Grand Prix appearances as a wildcard entrant in 1996, before contesting his first full 250cc World Championship season in 1998. His early results were modest — a fifth place in Argentina in 1998, another fifth at Catalunya in 1999, and nothing higher than sixth in 2000 — but the groundwork for a breakthrough was being laid.
The 2001 season proved transformative. Riding for the Safilo Aprilia team, Rolfo finished fourth in the championship, scoring three podiums across four mid-season races including second places at Mugello and Donington Park, and third at Catalunya. He failed to score points only twice in the entire campaign, announcing himself as a genuine title contender.
In 2002, Rolfo switched to the Fortuna-Honda Gresini team and produced the most consistent campaign of his 250cc career. He scored five second-place finishes — three of them behind the eventual champion Marco Melandri — and failed to score points only once, earning third in the championship overall.
The 2003 season brought Rolfo his closest approach to a world title. After Fausto Gresini chose to concentrate resources on the MotoGP class, Rolfo moved to a team managed by Daniel Amatrian, retaining the Fortuna sponsorship. He won at Sachsenring and Phillip Island and entered the final race with a mathematical chance of the championship: victory combined with Manuel Poggiali finishing outside second place would have been enough. The scenario did not materialise and Rolfo finished seventh in the race, ending the year as runner-up. He did, however, finish ahead of that season's most prolific race winner, Toni Elías, who placed third overall.
A difficult 2004 followed. Rolfo won the Spanish Grand Prix but added no further podiums, slipping to eighth in the standings.
With no progress in 250cc to build upon, Rolfo stepped up to MotoGP in 2005 with the D'Antin Ducati team. The circumstances were challenging from the outset: he was running year-old machinery on Dunlop tyres widely considered inferior to rivals, had no teammate to share data with, and the team lacked the testing budget to compensate. Rolfo scored points in nine races, with a best result of tenth, and finished 18th in the championship. It was a single season in the premier class.
Unable to secure another MotoGP ride, Rolfo moved to the Superbike World Championship in 2006 on a privateer Ducati with the Caracchi team. He showed early promise with a fifth place and two seventh-place finishes in the opening rounds but faded over the rest of the season, finishing 16th overall.
For 2007, Rolfo joined the HANNspree Ten Kate Honda team alongside the reigning 2004 Superbike champion James Toseland. He achieved a career-best fourth place at both Monza and Silverstone and finished eighth overall in the standings — a solid result, though inevitably overshadowed by Toseland's championship victory that year.
After Ten Kate Honda did not retain him for 2008, Rolfo signed with Althea Honda, carrying Hannspree sponsorship across. The season was disrupted by an injury that caused him to miss the Monza round. Despite flashes of speed — including a strong wet performance at Donington Park before an incident involving Leon Haslam ended his race — he was not kept for 2009.
Rolfo joined the new-to-WSBK Stiggy Racing Honda team for 2009, again alongside Haslam. His tenure was short-lived: he lost the seat after the Qatar round of the season to John Hopkins, effectively ending his professional racing career.
Roberto Rolfo's career traced an arc common to many talented satellite-team riders of the 2000s: genuine podium speed and a championship runner-up position in 250cc, followed by the difficulties of making progress with underfunded machinery in the premier class. His 2003 campaign remains the high point — two wins, a shot at the title on the final day, and a clear victory over that season's most prolific race winner in the standings.