Alexandra Reeve Givens, 31, gave birth to Christopher Russel Reeve Givens on 13 June and he weighed 8lb 3oz, according to Today.
A representative for the family told People magazine: "He was named after his grandfathers on each side. The entire family is thriving during their first few weeks home."
The couple shared a photo of their newborn son with the magazine.
Alexandra Reeve Givens met her now husband, Garren Givens, 33, while studying Law at Yale University.
Christopher Reeve had two children with his partner Gae Exton - Alexandra Reeve Givens, 31, and Matthew Reeve, 35.
However in 1987, Reeve and Exton separated, and Reeve soon met Dana Morosini, who he later married in April 1992.
Christopher Reeve was paralysed during an equestrian competition in 1995 and he and his wife created the Christopher And Dana Reeve Foundation, which is dedicated to curing spinal cord injury.
The foundation aims to fund researching and improve the quality of life for people living with paralysis through grants and information.
The new mother told People her newborn son is already wearing a "Team Reeve in training” T-shirt to support the work of the foundation.
Christopher Reeve died in 2004 of cardiac arrest, aged 52.