The former WBO world champion was flattened inside seven seconds of the main event at Manchester’s AO Arena after being forced into the corner and hit behind the ear with a huge looping right hand.
Chisora’s unrelenting pressure and energy-sapping body punches initially made it a very uncomfortable night for Parker, who is looking to get back into world title contention after a string of low-profile victories in the aftermath of his defeats by Anthony Joshua and Dillian Whyte in 2018.
However, he recovered in the second half of an entertaining contest, showcasing his superior technical skills and picking up enough rounds to take a split decision victory.
Two judges scored the fight 116-111 and 115-113 in Parker’s favour, while a third had it 115-113 in Chisora’s favour.
It was a second successive loss for the 37-year-old ‘Del Boy’, who was also outpointed by Oleksandr Usyk in October.