Tamada's competitive roots lie in Japanese domestic racing. After winning a regional 250cc championship in 1994, he spent four years in the main All Japan Road Race GP250 series, finishing as high as fourth on a private bike in 1998. He transitioned to the MFJ Superbike championship in 1999, consistently finishing in the top five over the following years.
His international breakthrough came as a wild card entry in the Superbike World Championship round at Sugo. In 2001, he upset the regular competitors by winning both races at the circuit, and followed up with another race victory in 2002 — making him one of only three riders to win a race that year, alongside Colin Edwards and Troy Bayliss.
Tamada's impressive wild card performances earned him a full-time MotoGP seat with Pramac Honda in 2003. The debut season was a learning exercise, with a best result of third place at the Brazilian Grand Prix and two front-row starts, finishing eleventh in the overall standings.
For 2004, he joined Sito Pons' Camel Honda squad and delivered his finest MotoGP campaign. He won at the Brazilian and Japanese Grands Prix, finished sixth in the championship, and was notably the only Honda rider running Bridgestone tyres — a combination that appeared to complement his aggressive riding style.
The newly formed Konica Minolta Honda team was built around Tamada for 2005, switching him to Michelin tyres. A broken wrist suffered early in the season hampered his championship challenge, though he did manage a third place at his home Japanese Grand Prix. The 2006 season brought further misfortune: at the Sachsenring, Tamada was running inside the top six when he was struck by the riderless machine of Kenny Roberts Jr., who had crashed in front of him.
In 2007, Tamada joined Tech 3 Yamaha alongside French rookie Sylvain Guintoli, running on Dunlop tyres. He was generally outpaced by his teammate throughout the season and finished eighteenth overall, after which no MotoGP seat was available for him.
With MotoGP options exhausted, Tamada returned to Superbike competition in 2008, signing with the Italian factory-supported PSG-1 Kawasaki Corse team, riding the new Kawasaki ZX-10R alongside Regis Laconi. For 2009, the factory Kawasaki support moved to the English Paul Bird Motorsport team, and Tamada continued as a factory-backed rider alongside Australian Broc Parkes. In October 2009, Kawasaki announced that his contract would not be renewed, with former MotoGP rider Chris Vermeulen taking his place.
Tamada made a brief WSBK return in 2010 with the Reitwagen BMW team at Portimao, retiring from the first race and finishing nineteenth in the second.
In endurance racing, Tamada was a notable performer at the Suzuka 8 Hours. In 2011, riding for Musashi RT Harc-Pro alongside Tadayuki Okada and Takumi Takahashi, his team finished third — roughly ninety seconds behind the winning side.
In 2012, Honda appointed Tamada as the official trainer for the inaugural Asia Dream Cup season, a development series using Honda CBR250R machinery where two riders from each Asian country were selected with a pathway to World Championship competition.
For 2013, Tamada took a full-time ride in the Asia Road Racing Championship's Supersport 600 class with MUSASHi Boon Siew Honda Racing, replacing the departing Ryuichi Kiyonari. He scored his first win in the class at Round 3 and was competitive before suffering serious injuries — fractures to the left clavicle, scapula, and ankle, as well as a partial amputation of the left middle finger — in a crash during Suzuka 8 Hours practice. He returned for the 2014 season, finishing sixth in the Asia Road Racing Supersport 600 standings.
Tamada remains one of the most distinctive figures in Japanese motorcycle racing, a rider whose style was ideally suited to Bridgestone rubber in an era when Michelin dominated the MotoGP grid. His dual-championship race victories across both MotoGP and World Superbike stand as testament to his ability at the highest levels of international motorcycle competition.