A graduate of the Hughes Insurance Ulster Academy, Marshall made his provincial debut in October 2010 against Munster, and he has gone on to amass 76 appearances in an Ulster career that has yielded 14 tries so far.
He made his international bow in the 2013 Six Nations Championship against Scotland. He has gained another five Ireland caps since, and his excellent form this season was rewarded with a call-up to the Six Nations squad, along with fellow Ulster centres Stuart McCloskey and Jared Payne.
Marshall says that his desire to win silverware had a big bearing on his decision to stay at Ulster:
"It is always a privilege for me to play for my home Province so I'm delighted to be staying on for another couple of seasons. We have a strong squad that is only getting better, and with the coaching team that we have in place, I believe we are well-positioned to challenge for silverware in the near future. We have come close to winning something over the past few seasons so there is definitely some unfinished business."
Ulster's Director of Rugby, Les Kiss, said:
"We're delighted that Luke has committed his future to us, particularly given that there was a high level of interest in him. Luke is one of our core group of indigenous players which is the bedrock of this squad and, at just 24, we believe that his best rugby is still ahead of him. He is an outstanding professional and a really good person to have in the squad.
"Luke has been in superb form for us this season in both the PRO12 and in Europe. His clever running lines and strong ball-carrying have been a real asset to us in attack, particularly during our European campaign in which he scored three tries. He has consistently demonstrated his ability to distribute the ball from first or second receiver which has really benefitted Paddy Jackson. Defensively, he has also excelled and he has forged good relationships with everyone he has played alongside in midfield."
It was also confirmed today that winger Rory Scholes will depart Ulster Rugby at the end of the season to join Edinburgh.
Scholes, also a graduate of Ulster's Academy structure, has played 22 times for the Province, registering five tries.
Commenting on his departure, Kiss said: "It was obviously a tough decision for Rory and it's disappointing to lose a player of his quality.
"Our Academy has done a great job in producing local young talent that has gone on to perform well at PRO12 and Champions Cup level. Rory's departure will give more opportunities to our current crop of young players such as Jacob Stockdale, Jack Owens and Robert Lyttle.
"We wish Rory well on his move to Edinburgh."