However, whispers of a potential return have swirled ever since, fuelled by Vettel's own recent comments and speculation surrounding vacant seats on the grid.
This opens up a prime seat at Mercedes, a team very much in contention despite their struggles in recent years.
With Red Bull's driver situation also in flux due to Sergio Perez's expiring contract, the possibility of a Vettel return has become a major talking point.
Vettel on potential F1 return and talks with Mercedes
In an interview with Sky Sports, Vettel addressed the ongoing speculation, admitting to being open to a return under the right circumstances.
"Well, potentially I am because I haven't got a drive, but they question is, am I looking for one? I think it depends on the package," he said.
"I retired from Formula 1 not to come back, but I also did say that you never know. So I think it still stands.
"Obviously, there's things that I miss, which is mostly the competition. And things that I don't miss, so that hasn't changed. Obviously, life is very different if you're not involved and I do enjoy that still," the four-time champion continued.
"You never know where life is taking you, so maybe it takes me back behind the wheel, maybe it doesn't."
Vettel also revealed conversations with Mercedes boss Toto Wolff, though not specifically about the vacant seat.
"I've had conversations with him (Wolff), not really about the seat. We did speak about the whole situation in short as well.
"But I did speak to others as well because I'm still keeping in touch every now and then. I have some projects and ideas together with F1. We'll see if they will turn out or not.
"So I am staying in touch. I don't know. It has to be a couple more phone calls and conversations, I guess, to really find out a little bit more. But for sure it's one of the best seats on the grid.
"Performance wise, Mercedes has a great track record, struggling a little bit in the last years, but then struggle and you're still second and third in the constructors' (championship), it's not like you're racing in no man's land."