Molinari cannot be denied a debut now that Ross McGowan is out of the final counting event, the Johnnie Walker Championship at Gleneagles, with a shoulder injury.
"It feels great, but maybe it's not the best way to make the team," said Molinari, who could yet be joined by his brother Edoardo in Colin Montgomerie's Team. "I feel sorry for Ross.
"It's been a dream - one of the goals for the season - and I used to look at it as something I would never achieve."
Molinari was sent a text message by coach Dennis Pugh on Sunday night saying he had qualified, but that changed on Monday when Miguel Angel Jiménez changed his mind about taking the week off.
"I said 'never send me a text like that again'."
The first Italian to make the Ryder Cup was Costantino Rocca. He played in 1993, 1995 and 1997, famously beating Tiger Woods in singles at Valderrama.
Molinari won the Omega Mission Hills World Cup with his brother in China in November, and Edoardo could join him if Captain Montgomerie gives him a wild card on Sunday.
Vice Captain Paul McGinley was full of praise for the 27 year old after he secured his place at The Celtic Manor Resort.
"He's had a great season," said the Irishman. "He reminds me a lot about myself when I made my teams, he's been very consistent, seems to be top ten every week, there and thereabouts and he'll be a great asset because he's a guy that can blend with anybody.
"Great personality, easy going, no big problems, no big dramas with him. So he'll be an easy guy to play with whoever plays with him."
Molinari joins Lee Westwood, Rory McIlroy, Ian Poulter, Martin Kaymer, Graeme McDowell and Ross Fisher in confirming his place.