The baby boy was born around 6pm on the bathroom floor of their home in Gloucestershire, South West England, after arriving ‘very quickly’.
“He ran to the gym, grabbed a mat, got into the bathroom, put the mat on the floor, towels down, bracket, bracket, bracket,” Tindall said.
The baby, named Lucas Philip, weighed 8 pounds 4 oz at birth, a spokesman for the couple told CNN.
The couple’s other two children, Mia Grace and Lena Elizabeth, were not home for the new arrival on Sunday, but have since seen him and are “over the moon,” said Mike Tindall.
The midwife, who was to meet them at the hospital, was on the scene quickly because she was not far away, and a second came “when the head arrived,” he added.
Zara is feeling well, he said, and is taking the baby for a walk.
“She was a warrior, as always, they always are,” Tindall said. “We can never judge a woman in terms of what she has to go through giving birth.”
He said there were benefits to giving birth at home. After Lucas’s arrival, Tindall watched an old rugby game and golf with his new son.
An accomplished rider, Zara Tindall has won a silver medal in a team event at the 2012 London Olympics.
She met her future husband at the 2003 Rugby World Cup when he was playing for England. The couple married in Edinburgh in 2011.
CNN’s Amy Cassidy contributed to this report.