Darren McIntyre, 47, punched Mark Bamber after being called to his home in Ainsdale, Southport, on 19 June 2019.
He was sentenced at Liverpool Crown Court to 19 months in jail for assault and perverting the course of justice.
Two other officers were jailed in May and another received a suspended sentence after lying to cover up the assault.
McIntyre’s colleagues Laura Grant, 36, and Lauren Buchanan-Lloyd, 26, turned off their body-worn cameras while the assault took place.
The pair, and another colleague Garrie Burke, 44, were convicted of perverting the course of justice.
The court heard McIntyre, of Southport, repeatedly punched the man “in temper and in anger” after being called to a property in Cherry Road.
The arrested man was later released without charge.
Deputy Chief Constable Ian Critchley apologised to the victim and said it was “disheartening” for other officers who “give their all day-in-day-out”.
“Constable McIntyre has not only let himself down, he has also let down his colleagues and the communities we are there to protect,” he said.
Other colleagues did raise concerns about the incident and the four officers were not the majority, he said.
Burke, of Maghull, and Grant, of Waterloo, were both jailed for 15 months.
Buchanan-Lloyd, of Higher Bebington, who had been a police constable for five weeks at the time, was given a nine-month sentence, suspended for 18 months, for the same offence.
All four officers are due to face internal misconduct proceedings.