
Wurz, 33, originally quit F1 after the penultimate 2007 race in China after 11 seasons and 69 races in the sport, citing doubts over his own commitment. He drove for Benetton, McLaren and Williams.
At Honda, the Austrian will test the car and provide the backup role for Rubens Barrichello and Jenson Button.
"We are delighted to welcome Alex to the Honda F1 team and very pleased to have secured one of the most experienced development drivers in Formula One to support our race driver pairing," said Honda team boss Ross Brawn.
Wurz said: "This is an excellent opportunity to play an important role in the development of the team going forward. My three previous teams have all been world championship winners and I hope to be able to contribute to Honda's ambitions.
"The chance to work with one of the best brains in F1 in Ross Brawn is very exciting, as is the level of resources that the Honda team has at its disposal," he said.