Earnhardt, 32, who has called a Wednesday news conference to announce his plans, decided in May to leave the racing team founded by his late father, the Dale Earnhardt Inc. Nextel Cup team. He reportedly has been looking for a new racing team since.
Earnhardt wanted to remain in a Chevrolet and joining Hendrick would allow him to do so.
Teresa Earnhardt took control of DEI after her late husband and seven-time stock car racing champion passed away. She reportedly had been at odds with her stepson, who asked for a controlling interest in the team.
Earnhardt, the 2004 Daytona 500 champion and NASCAR Busch Series champion in 1998 and 1999, is 14th in this year's Nextel Cup Standings.
Earnhardt has driven Nextel Cup cars for DEI since 1999. He has 17 race victories.