Both will represent the USA in the ‘Nations Cup’ section of the end-of-season event, where they will hope to re-gain the trophy their country last won in 2002.
"I'm looking forward to getting out there and representing the USA and NASCAR," said Johnson, 31, who is on course for his maiden NASCAR Nextel Cup championship this season.
"Typically you don't get to race against the top competitors from F1, rally and Champ Cars but this event allows you to with it's creative format."
Race of Champions 2006
Ekstrom wins Race of Champions
16/12/2006 AT 19:47
Pastrana, 23, is a legend in his homeland for his exploits in Motocross, but has switched to four wheels this season and recently claimed the North American Rally Championship.
He has competed in the event twice before and hopes that this year will be his most successful time yet.
"I'm glad to have another opportunity to race with the best drivers in the world," Pastrana said.
"Last year I was a bit off the pace but with more experience under my belt I expect to be a contender."
The pair join the likes of Sebastien Loeb, Colin McRae and Jenson Button in the line-up for the December 16 event at the Stade de France.
Race of Champions 2006
Loeb cruises into RoC semi-finals
16/12/2006 AT 19:02
Race of Champions 2006
Finland win RoC Nations' Cup
16/12/2006 AT 16:33