The 20-year-old central midfielder was released by Reading earlier this summer but impressed in a recent successful trial period with the young Whites.
Shaughnessy, a Republic of Ireland international at youth level, then signed a one-year deal to join United’s Development Squad and was brought on as a second-half substitute during Friday night’s 1-1 draw for United’s under-23s against Crewe at Elland Road.
The match was watched by around 100 spectators and Shaughnessy faces stiff competition to earn a place in the first XI at a club chock full of midfielders. That, though, is not preventing the Irishman from being focused on forcing his way into head coach Garry Monk’s plans in the next few months.
“I was delighted to get a chance to have a run out at Elland Road,” said Shaughnessy.
“It was a great feeling and I was happy to be on that pitch and playing in front of that crowd.
“It was a little bit small but hopefully I will play in front of a bigger crowd. That’s the aim.
“I have got to take it step by step and I just need to get my fitness up now with the under-23s and match fitness.
“Then hopefully I can catch the manager’s eye and get given a chance to train with the first team and go from there. I’ve not had that as of yet. I have just been training with the under-23s but hopefully I will get that in the not too distant future.”
Explaining his style of play, six-foot-two Shaughnessy added: “I’m a centre midfielder who can get forward and back.
“I prefer the no 8 role and I like to think I can score goals as well.
“It’s a huge year for me and hopefully that transition from youth/under-23 football to first team. I’m hoping I can push on now in the next few months.”
Shaughnessy played 31 minutes on Friday after coming on for Jack McKay.