Murphy spent the second half of last term with the Whites, making 13 appearances in all competitions and scoring twice.
He stayed at Newcastle this season to provide cover for the first team but had been limited to a handful of appearances off the bench.
That changed on Tuesday night when he was handed a first start, coming up against Qarabag in the Champions League at St James’ Park.
"Obviously, a brilliant feeling for myself. It's not been an easy year - I haven't played much football, and as a footballer, obviously, you're not happy when you're not playing,” he told Chronicle Live.
"I've just always kept the faith and hoped I would eventually get a game, and obviously in the Champions League I couldn't have asked for a better occasion to do it on, so I'm happy."
It was a big moment for Murphy, who headed to England in 2023 after catching the eye while playing for Galway in the League of Ireland.
"Obviously from a young age, it started from there really and then the last three years I've been here, starting in the Academy, playing games for the Under-21s and training,” he recalled.
“Then getting the move up to the first team two years ago, and I've just been training and trying to improve my game and obviously get a chance.
"It was my first start, so obviously it's a big moment for me and all the work you've put in for one moment like that.
“It just gives you a bit of relief really, that all the work is not just for nothing, you've actually got something out of it, so it's a good feeling.”
Newcastle are back in league action against Everton this weekend. Eddie Howe’s side currently sit 11th in the Premier League table.