The last man to be sentenced over a New Year's Eve confrontation at Rye which ended in the "one-punch" death of David Cassai has been jailed for two years and three months.

Supreme Court Justice Elizabeth Hollingworth said Thomas McCloskey-Sharp had been involved in a "very cowardly attack".

David Cassai was killed by one punch on New Year's Eve 2012.

"Although it was spontaneous and of very short duration, this was nevertheless a serious affray, involving a violent, frightening and completely unprovoked attack by you and your friends on another group, in the middle of the night, on a public street, at a busy time of the year," Justice Hollingworth said on Friday when jailing McCloskey-Sharp for two years and three months with a non-parole period of 17 months.

Dylan Closter, McCloskey-Sharp's friend, was the man who threw the punch that killed Mr Cassai in the early hours of December 31, 2012. McCloskey-Sharp, 26, who ran over to help attack Mr Cassai's friends, pleaded guilty to one count of recklessly causing injury and one count of affray.