The 22-year-old Familia is considered one of the Mets' top pitching prospects. He compiled a 9-9 mark with a 4.73 ERA in 28 starts at Triple-A Buffalo before being called up on Tuesday.
Familia said he was nervous, but that he managed to stay composed.
"After I threw the first strike, I felt better," Familia said.
Familia was born in Santo Domingo in the Dominican Republic and still struggles speaking English. But he said he was proud of his initial performance, especially the strikeout of Berkman.
"I felt excited because I know he's a superstar," he said. "I just tried to throw my [pitches] and get an out."
Mets manager Terry Collins was impressed with Familia's six-minute performance, opening his postgame news conference gushing about the effort.
"I'm very happy for him, he pounded the strike zone," Collins said. "It was a great sign in his first outing. I was really excited for him."
Familia has spent most of his Minor League career as a starter, but Collins wants to ease him into a relief spot for the time being.
"I don't know where he's going to fit, what role he's going to be in as time goes by," Collins said. "But I wanted to get him in there as soon as I could."
Familia, along with Matt Harvey and Zack Wheeler, are the top pitching prospects in the organization. Familia has the ability to blow hitters away, but he needs to work on his other pitches.
"When you've got a power arm like that, it's all about command," Collins said. "He'll let it fly. When he does, he's effective."
Familia, who had 128 strikeouts in 137 innings for Buffalo, saved the baseball from his first outing and plans on giving it to his parents, who are coming to watch him this weekend.