Team owner Tim Martin has long been a road-racing supporter and 24-year-old Harrison will ride the team's R6 Yamaha at the TT as well as the other international meetings - The North West 200 and Ulster Grand Prix.
Harrison recorded a tremendous victory at this year's Southern 100 aboard an R6 Yamaha in one of the Supersport races, and his seventh place at the TT in the second middleweight encounter, as well as his first TT podium in the BikeSocial.co.uk Lightweight TT, sets him up well for a shot at a debut TT Supersport podium with Mar-Train in 2014.
Harrison was at Brands Hatch on Sunday to secure his deal and also watch Mar-Train Racing lift this year's British Supersport title with Stuart Easton. The affable Bradford man said of his new deal: "Yeah, it's unreal to have tied up a contract with Tim and Sonya and the Mar-Train team for 2014."
Harrison added: "We had a good year on a 600 Yamaha this season, but hopefully we can do a better job on what is definitely a stronger package with the Mar-Train bike. I've always wanted to stick with the same bikes that I was on, so the Mar-Train deal is perfect for me as they have so much more data and experience. Yeah hopefully we can have a good season."
Harrison will also take in the Southern 100 and Scarborough meetings with Mar-Train with some additional ad-hoc appearances to be discussed, and as soon as next week, the Northern Ireland team will be announcing his team-mate for 2014.
Team owner Tim Martin said of his acquisition: "The plan for 2014 was to spread our wings a little and get involved in the International Road Racing scene. We have dabbled before but with Dean on-board and another rider secured – who we will be announcing next week – I believe we can challenge at the sharp end next season on the roads with two very exciting and talented riders. It's all about exposure and return for our sponsors, both old and new, and the road races that we have chosen will play an important supporting role to our 2014 British Supersport campaign as defending champions."
TT and Motorsport Development Manager Paul Phillips commented: "Mar-Train are joining the TT paddock on the back of an excellent season and will be a welcome addition to the TT. It is another sign of the TT's growing strength that we are welcoming a current British Championship winning team. With Dean on board they will be right at the front of the pack and will contribute significantly to what is already building up to be hugely competitive Supersport races."