As a relative unknown on the world stage, the right-back will be looking to challenge Rafael and Marnick Vermijl for a starting spot at Old Trafford. Before he can do that, Varela will need to endear himself to the United fans with strong performances in the youth ranks.
Let's not get ahead of ourselves. For now, here's a selection of handy facts on the Premier League champions' newest prospect:
Place of Birth: Montevideo, Uruguay
Weight: 152 lbs
Previous Clubs: Peñarol (2010-13)
Senior Career: Varela made just one senior appearance for Peñarol. This came on 5 June, 2011 against his hometown side Racing Club de Montevideo. Although Peñarol lost this game 1-0, Varela replaced Yefferson Moreira in the 67th minute in front of the Centenario fans.
Youth Career: Despite only playing one senior game, Varela has represented both the Uruguay U17 and U20 lineups. The defender has made nine U20 appearances since 2011 and set up the winning goal in the win over Chile U20s.
Varela has won four, lost two and drawn three of his nine games for the U20 side. He is set to represent his country at the upcoming FIFA U20 World Cup in Turkey.
Signing for Manchester United: Although Varela joins the English champions after Sir Alex Ferguson's retirement, he is undoubtedly a Fergie signing. United's new defender spent the last few weeks of the 2012-13 season on trial with the club and did enough to be offered a full deal.
Varela spoke highly of his initial experiences at the Carrington training ground. In an interview with South American radio station Tirando Paredes, he suggested Javier Hernandez will help him adjust to life in England (as translated by ManUtd.com):
I have trained with the first-team. I am very happy and I was received very well. It was a surprise to get the chance to test myself with Manchester United. I'm glad and happy, and grateful to Peñarol who allowed me to travel. I was treated so well and Chicharito helped me a lot.
Peñarol manager Jorge Da Silva believes Varela has done more than enough to merit a move to United, as reported by the BBC: "This is what he deserves. It is a shame to see him go but you can't deny him the opportunity to join a club like this."
Now that his transfer is confirmed, Varela's every appearance will be scrutinised with greater intensity at the FIFA U20 World Cup. He is set for a busy summer before linking up with David Moyes' squad across preseason.
The youngster's move is yet another example of United dipping into the South American market. He is likely to be used sparingly in the first team—perhaps in Capital One Cup matches—before seriously challenging Rafael for a place in the starting lineup.
Like Phil Jones and Chris Smalling, Varela needs to be versatile if he is to make an impression across his first couple of years with the club. Can the 20-year-old progress into a future United star? The Old Trafford faithful will hope so.