On medical advice, due to injuries sustained from a horrific smash in the IndyCar Grand Prix of Houston last month, Franchitti has been left with no choice but to bring the curtain down on his stellar career.
Winner of four IndyCar titles and three Indy 500s, Franchitti departs as one of the most decorated drivers in American motorsport history.
Via a statement, 40-year-old Scot Franchitti said: "One month removed from the crash and based upon the expert advice of the doctors who have treated and assessed my head and spinal injuries post accident, it is their best medical opinion that I must stop racing.
"They have made it very clear the risks involved in further racing are too great and could be detrimental to my long term well-being.
"Based on this medical advice, I have no choice but to stop.
"Racing has been my life for over 30 years and it's really tough to think the driving side is now over."
By his own admission, Franchitti is convinced that once he is fully recovered he will continue with motor sport in some capacity.
Paul Di Resta has no doubt his cousin still has plenty to offer.
Speaking to Press Association Sport in the paddock at the Circuit of the Americas in Austin ahead of this weekend's United States Grand Prix, Di Resta said: "It's now all about Dario's recovery.
"It's all about getting him back healthy and being there for him, and that is all we (the family) are there to do.
"I can't speak highly enough of his achievements. Tremendously proud, successful, a legend. What else is there to say? More so being part of the family.
"That's the thing that will keep Dario going, the fact he can come racing with the likes of me and Marino (Franchitti, younger brother). Being part of all that will drive him on.
"And he has a lot to offer to a racing team as an ambassador. I'll be shocked if he doesn't stay in the sport, as a consultant, a mentor. He will be a credit to somebody's team."
Di Resta believes Franchitti's achievements have shamefully gone under the radar in Europe simply because he has spent his career in the US.
"In Europe he is probably under-appreciated. Not enough people have stood up and taken notice of his achievements," added Di Resta.
"He is a 40-year-old man now and the title success he has is far more than any British driver has achieved recently.
"Out here (in America) he is what he is and fair play to him.
"He took some knocks, dusted himself off, and to sit there at 40 with four titles and three Indy 500s, I would like to be in that position - only 13 years to go!"
Jenson Button can recall one of his first meetings with Franchitti, a moment that resulted in a long-standing appreciation.
"Dario was one of the drivers I always looked up to as a youngster," said Button.
"I remember being at the NEC in Birmingham for an Autosport show, and when I was really young I went on to the arcade machines and tried to get the best time at the circuits.
"I thought I was really good, and I was really good to be to fair.
"This one time I'd finished, and then Dario jumped on and beat my time first time up, and I just thought 'Wow! He's superhuman!'
"And I still think he is as a human being. He's a proper legend of the sport.
"He's achieved so much, but he also carries himself so well. He's such a nice person, a lovely guy.
"It's a shame he is retiring because he is still very young at heart, but he's probably doing the right thing after such a big shunt.
"It's sad to see him go, but I'm sure he's still going to be around the sport."
Like Button, Hamilton was also naturally saddened to hear of Franchitti's decision when informed by Press Association Sport.
"I don't know him that well, although I've known him for years and he's always been a really pleasant guy," said Hamilton.
"He's come across as being very open, very straightforward, and what he's achieved in the sport has been great.
"I don't know how many injuries he's had - tonnes of injuries - going back to when he damaged his back on a bike.
"When he busted his back I was looking at the time to get a bike the same as his.
"It's a real shame because he still had some time to go in the sport, so I'm really sad to hear he's had to retire."