Henry was born in Fundenhall, Norfolk, England. Mary Croker, sometimes spelt Crocker, was the daughter of John Croker of Lyneham. She was born c1553. They married c1574. He died May 21, 1617 in Rosemeryn, Cornwall, England.

According to The Bishop's Transcripts at Exeter, Henry was buried May 21, 1617 at Budock, Cornwall.

National Archives (UK)
Reference: KNY 437 371 x 9
List of payments made [by Thomas Knyvett of Ashwellthorpe] to and for his cousin Henry Knyvett, (1564-1565).

Reference: KNY 438-444 371 x 9
Acknowledgements of receipt for annuity paid by Thomas Knyvett Esq. to his cousin Henry Knyvett gent. (described in 1573 as in Cornwall), (1565-1575).

Reference: KNY 459 371 x 9
Bond of Sir Thomas Knyvett of Ashwellthorpe to Henry Knyvett of Budock (co. Cornwall) for payment of £20, (1579).

Reference: KNY 463 372 x 1
Note by Sir Thomas Knyvett, Re discharge of debt of his cousin Henry Knyvett to one Gryffyn, (1590).