Like many auto racing drivers, he started his career in karting, first racing in 1993. After winning Australian, North American and Italian championships, he moved to Formula Renault in 2000. He won the Italian Championship in 2001 (winning 5 races) and finished 4th running a limited schedule in the Eurocup (with 2 wins in 6 races).
In 2002, he became test driver for the Toyota Formula One constructor. He started that year racing in the Formula 3000 series, but struggled and left his ride after 7 races. He finished the year in the German Formula 3 series, taking 3 podiums in the last 6 rounds.
He won the Formula Three Euroseries in 2003 (winning 8 races in the process). He became the Toyota F1 team's 'third' driver (ie, drove the team's test car on Fridays at Grands Prix) for the last third of the 2004 season, after previous third driver Ricardo Zonta was called up to replace Cristiano Da Matta.
There were rumors that Briscoe was set to race for the Jordan Grand Prix F1 team in 2005, due to the team's acquisition of Toyota power. Instead, Briscoe raced for Target Chip Ganassi Racing in the Indy Racing League, including a 10th place finish in the Indianapolis 500. He also made his Rolex Grand-Am debute with Ganassi at the 24 Hours of Daytona. He took pole position at Sears Point, but struggled on the ovals and was involved in several crashes.
On September 11, 2005 he was involved in an enormous crash at Chicagoland Speedway, breaking both clavicles among other injuries. He was released from the hospital on September 19 and following some initial treatment in the USA, moved to the specialist Formula Medicine facility in Viareggio, Italy, for the bulk of his rehabilitation. It took 8 weeks for Briscoe to recover from the injuries he sustained in the crash. His official web site announced his return to the USA on November 14, 2005. Following the incident Ryan was nicknamed "Briscoe Inferno".
Briscoe was dropped by Ganassi for 2006, replaced by 2005 IRL champion Dan Wheldon. During the winter, he tested with fellow Australian and Champ Car owner Kevin Kalkhoven's PKV Racing team. Briscoe also tested for the Mi Jack Conquest team. Briscoe competed in the 2006 24 Hours of Daytona with 2005 Champions Wayne Taylor, Max Angelelli and Emmanuel Collard, but the team withdrew due to accident damage before Briscoe's turn to drive.
In 2006, Briscoe was announced as an endurance driver for Holden Racing Team, set to partner Jim Richards at the Sandown 500 and Bathurst 1000. He also drove in the A1 Grand Prix race at Laguna Seca in the USA for A1 Team Australia, scoring three points. At the Indy 500 he was a surprise late driver of the number 48 car for A J Foyt Racing - the deal was so late he was still having his seat fitting with less than half an hour of Bump Day qualifying left, and he never got out on the track to attempt a qualifying run. He returned to the IRL the following week and drove the number 5 Dreyer & Reinbold Racing Dallara to a third place finish at Watkins Glen International, a road course. He return to the Dreyer & Reinbold team on a three race deal for the short speedways in the second half of the season, but recorded DNF's in 2 of his 3 races with the team. He then was tabbed to replace the injured Cristiano da Matta in the final two races of the Champ Car season for the RuSPORT team, including his home country's race at Surfers Paradise.
For 2007 Briscoe signed a deal to drive for Penske Racing's Porsche LMP2 car in the American Le Mans Series and was named to a ride in the Indy 500 in a car owned by Stephen J. Luczo and Jay Penske with equipment leased from defending '500' champion Penske Racing.