The Selecao looked nervous early on and it was no surprise when Real Madrid defender Marcelo put the ball into his own goal to hand Niko Kovac’s men an 11th-minute lead.
But with Brazil struggling in front of an expectant home crowd it was Neymar who came to the rescue. He equalised with a 29th-minute drive with Croatia's Stipe Pletikosa slow to react.
And he then gave Brazil the lead from the penalty spot, which the goalkeeper again should have saved, after Japanese referee Yuichi Nishimura controversially pointed to the spot following Dejan Lovren's tangle with Fred.
Oscar then made the points safe late on to give the hosts a flattering margin of victory.
"It was the best [opening match I could hope for]," Neymar told ESPN Brasil.” We wanted to win. And starting a World Cup with two goals gives me a great happiness.
"If you notice the goals, they were all a bit strange. I really did mean to put the ball between the defender's legs [for the first], but not for the shot to be as weak as it was. But the important thing is that it was a goal.
"How do I keep my cool for the penalty? It's a lot of practice, to hit the ball really strong. Their keeper gave me a little scare there, but the ball went in, thankfully."
Neymar was a touch fortunate to only see a yellow card for a first-half elbow on Real Madrid midfielder Luka Modric but the Barcelona star insists the caution won’t hinder him in the remaining group games.
"I will play naturally. I won't be thinking about it. If I do, it's worse," he added."Receiving a yellow card on your first match is hard. My elbow hit Modric and I wanted to apologise, because I didn't notice he was there.
"If the referee thought there was intention on my part he was right to give me the yellow, but there wasn't."