Lucas, is currently 22nd in line to the throne. He is the Queen and the Duke of Edinburgh’s 10th great-grandchild
The baby’s birth comes just a few weeks after Zara’s cousin Princess Eugenie had her son August on February 9.
A spokeswoman for the couple said: “Zara and Mike Tindall are happy to announce the birth of their third child, Lucas Philip Tindall.”
Mr Tindall said the royal baby – the Queen and Philip’s 10th great-grandchild – was born on the bathroom floor after the couple were unable to make it to hospital.
“Arrived very quickly. Didn’t make it to hospital. On the bathroom floor,” he said on The Good, The Bad & The Rugby podcast.
He described how he rushed to get a mat for his wife.
“So yeah, it was running to the gym, get a mat, get into the bathroom, get the mat on the floor, towels down, brace, brace, brace.”
The newest addition to the Tindall family is a younger brother to seven-year-old Mia and two-year-old Lena.
Mike Tindall had joked about wanting a boy this time around.