The 33-year-old striker, who returned to play for South Australia's Adelaide United in 2007 after a decade with Germany's 1860 Munich, cited a tiring body for his decision.
"I've had a long career and it has been a good one and I'm still as eager as ever but the body just can't keep up anymore, so I think it would be a good time to call it a day," Agostino said.
"At the end of the day when I look back, I've had 18 years of professional football so I think that's a good innings. My dream was always to come back and play in my home town and I managed to do that, just not as many games as I would have liked, but the season's not over yet."
Adelaide United retain a one-point lead at the top of the A-League competition, with seven rounds remaining before the 21 February grand final.
Agostino's return to Australia has been marred by injury and illness, including a bout of chicken pox, and the player said that, while he thought the decision to retire would be difficult, "my body made the decision for me".
He played in Switzerland during the early 1990s before heading to Bristol City from 1995-1997. From there he spent a decade at 1860 Munich for whom he played in the German club's 2000/01 UEFA Cup and UEFA Champions League campaign.