Toivonen, who scored for Sweden against Germany at the recent World Cup in Russia, said he was excited after signing a two-year deal.
"I know Melbourne Victory is a big club in Australia, they won the championship last year and they're playing in the (AFC) Champions League," he said.
"If you go on an adventure, you want the possibility of winning, you want to win something."
The 32-year-old used to play for Dutch giants PSV Eindhoven before moving to France's Ligue 1 with Rennes and Toulouse. He also had a season at Sunderland in England.
"Ola brings proven quality to our attack and he will play a big role in leading our forward line this season," said Victory coach Kevin Muscat.
"He is exactly the kind of player we wanted to recruit, he is an accomplished striker so I'm delighted he's decided to come to Melbourne."
Japan's former AC Milan playmaker Keisuke Honda joined the club earlier this month ahead of the 2018-19 A-League season which kicks off in October.