The new bridge is named in honour of the 40th anniversary of friendship between the Croatian and the Italian city.
The red ribbon was cut together by Karlovac Mayor Bozo Joha and Alessandria Mayor Mara Scagna, who said that as soon as a public facility was built in her city it would be named after Karlovac.
Present at the red-ribbon cutting ceremony was also Croatian President Stjepan Mesic.
The construction of the 100-metre-long bridge, worth 32 million kuna (approximately 4.3 million euros), was financed by the Croatian Highways company.