Team co-owner Waltrip, who once nicknamed Reutimann "The Franchise," thanked the driver in a statement. Reutimann has been with MWR since its inaugural 2007 season, and gave MWR its first victory in 2009.
"David has been a significant part of Michael Waltrip Racing since the very beginning and will forever be a part of our heritage," Waltrip said. "We want to thank David for his contribution to our growth and success over the past five years and wish him well in the future."
In 168 Sprint Cup Series starts, Reutimann has two wins, 25 top-10s and four poles.
Reutimann this season has just two top-10s and is 28th in the Sprint Cup standings.
Martin is not expected to run a full season. He could share the seat with Waltrip, who has made seven starts the last two years.