Green knocked ‘The Bronx Bomber’ down once in the third and twice in the fourth before the referee intervened in the next round for his first victory in three fights.
Spurred on by a rabid and partisan crowd in Perth, Green took full control of the fight after a tentative and even first couple of rounds to start, and was hoisted aloft by his defeated adversary following the bout in a nice touch.
The 39-year-old could not be drawn into discussion on whether or not he would indeed hang up his gloves, though American Santiago commented that Green had “treated him with respect” and that he “hopes Green does not retire”.
"I'm just going to relax," Green said after the fight, "I've worked and persevered and hung in there, and I've done it for you guys."
Turning his attention to Santiago, he added: "I've knocked some people out, you should have been asleep with some of the shots you took tonight but you are one tough hombre."
On the undercard, Pieter Cronje also won by TKO in the last of his ten rounds against Oscar Siale, claiming the vacant IBO international cruiserweight title in the process, while Matt Garlett inflicted a devastating second-round knockout upon Qui Xiao Jun in featherweight action.
Perth's own Brandon Ogilvie defeated Kayne Chapman in three rounds, while former kickboxer Alex James made a successful professional debut over four rounds against Shane Quin, despite the announcer initially declaring the latter as the victor.