In his last post on Twitter, he said: "Time to hit Queensland Raceway today, should be fun, hope there aren't too many kangaroos like at Bathurst!" a reference to Australia's premier endurance auto racing event last weekend.
Hartmut Kristen, Head of Motorsport at Porsche, described Edwards "one of the most popular and successful" drivers in the Porsche series. Edwards won the Nurburgring and Dubai 24 Hours this year.
The British Motor Sports Association said: "Sean was a hugely promising young racer who came through the junior formulas in Britain before making a career in international sports car racing,"
Former F1 driver David Coulthard posted a tweet saying: "Shocking news about Sean Edwards' passing, top man and super talented racer, condolences to his nearest and dearest."
Edwards had told fans via social media he would be in Australia on a short visit before returning for the last two races of the Supercup series.
Calls to the Queensland Raceway and chief executive John Tetley seeking comment were not returned. Domestic media reported it was the second fatal accident at the circuit in five months, with a 23-year-old motorcycle racer killed after a collision with another motorcycle in June.
Brisbane's The Courier-Mail newspaper identified the injured local driver as Will Holzheimer and said he was having a coaching session with Edwards.
Queensland state police and the Workplace Health and Safety unit are investigating.
Sean Edwards started his racing career in 2003 in Formula Ford, and later competed in Formula Renault UK, British GT and the FIA GT3 Championship before starting his Porsche Supercup career in 2008.
Allan McNish, a three-time Le Mans 24 Hours winner, told the Press Association that he had followed Sean Edwards' career closely and 2013 was shaping up as his breakthrough season.
"He was a guy who loved life, loved racing, loved cycling, was strong and fit," McNish was quoted as saying. "He was just a really nice young guy who was making his mark on the sport, and socially a really good guy to be around."