Full-back Marc Tierney joined Norwich City from Colchester on 13th January 2010 for an undisclosed fee, signing a two and a half year contract. He will provide competition to Adam Drury and Steven Smith for the left-back position.

Tierney rose through the youth ranks at Oldham Athletic, making his professional debut for Oldham in a Carling Cup match in August of the 2003–04 season, against Scunthorpe United. In December 2004 he went to Carlisle United on loan for a three month spell under Paul Simpson.

In January 2007, Tierney was signed by Shrewsbury Town in a two and a half year deal. He was a regular in the Shrewsbury side during the closing months of the 2006–07 season, as Town reached the League Two playoff final at Wembley. Notably, Tierney was sent off in the dying minutes of that game, making him only the second player to suffer this fate at the new stadium

In spite of Shrewsbury's disappointing 2007–08 season, Tierney enjoyed excellent personal form. His consistently dependable performances earned him both the fans' and players' player of the year awards

On November 27, 2008 Tierney joined Colchester United on an initial five-week loan. The move was made permanent by manager Paul Lambert in the January 2009 transfer window. He made 74 appearances for the U's before joining Norwich, scoring once.

At the end of his first season, Norwich won promotion to the Premiership, on 2nd May 2011 with a 1-0 win at Portsmouth with Marc playing a key role (16 appearances) in the Canaries' promotion challenge. He was also linked with a call up to the Irish squad

Impressive form in Norwich's opening start to the 2011/12 premier League season saw Tierney linked again withthe Irish squad, with Irish coach Marco Tardelli revealing that that Norwich City trio Wes Hoolahan, Anthony Pilkington and Marc Tierney are firmly on his international radar ahead of the Euro 2012 finals. The former World Cup winner, who was at Carrow Road to see the Canaries take on Arsenal, admitted he and Ireland manager Giovanni Trapattoni were weighing up all their options with regards to their final 23-man Euro2012 squad.

Tierney made 17 appearances during the 2011/12 Premier League season but missed the second half through injury.

After playing in the 5-0 defeat at Fulham on the opening day of the 2012/13 season, Tierney lost his place in the City first-team with further appearances limited to cup games. On 20th May 2013, City announced that they would not be renewing his contract when it expired at the end of June 2013. He had played 39 times for City. he was quikcly linked with a move to Bolton Wanderers. This was confirmed on 30th May 2013

Tierney was forced to retire from the professional game because of an anke injury on 24th April 2015. He had suffered a broken bone and ligament damage in a game against Yeovil in 2013 and undergone four operations

At the end of August 2024 he was appointed as Director of Football at Altrincham of the National League. Co-Chairman Bill Waterson said: "I am delighted to welcome Marc to Altrincham as our new Director of Football. As we continue to chase our ambition of a place in the Football League, Marc will bring to bear all of his extensive experience, his footballing network and his already evident drive and determination. He will bring a fresh perspective in support of the National League's strongest management team."

Tierney said ""Initially, I had some time away from the game, because the broken leg that ended my career took a bit of getting over. I qualified for the Republic of Ireland through my grandmother, and the injury happened just as I was getting word of a call-up from the manager Giovanni Trapattoni. On top of that, it needed five operations to put it right. When I decided I wanted to get involved again, I came back into it with a fresh pair of eyes. I called on a few contacts and arranged to shadow scouts, sporting directors and others working in recruitment to get an idea of how that side of the game worked. In addition, I spent 18 months doing a masters in sporting directorship under the tutelage of Dr. Ian Lawrence at The Etihad complex, which gave me a real insight into how clubs are run at so many different levels.

"Having done all that and gained first-hand experience of the role, I feel I am in great shape to work alongside the management team at Altrincham, a club that is going places and has a real buzz about it after the progress that has been made on and off the pitch over the past couple of years. It goes without saying that the relationship with the manager is key, and from the moment I first stood in front of Phil, I knew we wanted the same thing for the club. We spoke in a quite matter-of-fact way to learn more about each other, our thoughts and ideas about the way forward, and it was clear there was a mutual respect.

"I see my role as helping Phil and his management team in any way I can, continuing to strengthen that relationship and making sure everyone is working in alignment for the greater good of the club. We all have the same expectations and ethos.

"What Phil has done over the past couple of years has been exceptional, and the aim now must be to keep making the club better by getting the best out of each other and working closely together.

"Last season's achievements haven't gone unnoticed. They have created a momentum that has spread through the town and the community. You can feel it, and right now is a great time for pushing on, building on that momentum and on the buzz that is so evident at the club.

"It's a tough league to get out of, and we may have to manage expectations to a certain extent. But I have never been in a league and not tried to get out of it, and I know that, as a group, that is an objective we all share."