Born in Nova Gradiška, Vlaović started his professional career with Osijek in 1989 and moved to HAŠK Građanski in 1992, before going abroad to play for Calcio Padova in Italy, Valencia in Spain and Panathinaikos in Greece, where he retired in June 2004.

His biggest personal success at club level came when he topped the goalscoring charts of the 1993–94 Croatian First Football League, netting 29 goals for Dinamo Zagreb that season.

On 13 March 1996, he scored his first goals for the team in a friendly match against Korea Republic, netting a flawless hat-trick in Croatia's 3–0 victory.

He was subsequently added to the Croatian squad for the UEFA Euro 1996 finals in England, appearing in all of the team's four matches before they were knocked out by eventual champions, Germany, in the quarter-finals.

He was also added to Croatia's 23-man squad for the finals of that tournament, but was left an unused substitute in all three group matches as the team failed to qualify for the knock-out stages.