The two-time champion Alonso is widely regarded as one of the best drivers around but brought a frustrating few years with McLaren to an end with an 11th placed finish.
“It’s going to be a good memory, the whole package in Formula 1,” said Alonso. “A fantastic journey from a very young age until now, fighting always in any circumstances, in any car and I think achieving a lot of success that I never expected."
His talent could have brought even more success but bad decisions and bad luck cost him dearly over the years.
Alonso will now turn his attention to winning the Indy500, to go with victories in the Monaco GP and 24 hours of Le Mans to become just the second man to complete the motorsport 'triple crown'.
If he achieves that goal, a return to F1 – in some form – is not ruled out.
“Right now I’m not thinking to come back, that’s for sure,” said Alonso, “but I don’t know how I will feel next year.
"But for 2020, maybe I feel the need to do a full calendar in something, maybe full IndyCar, maybe full Formula 1, I don’t know, and maybe that’s the time to come back."
In his absence, the superb Hamilton will start as favourite for a third straight title and sixth overall.
"I've been able to be a better me all year long and I will continue to try to work on that and try to work on the energy that I'm projecting to people," the Briton said.
"I had a lot of fun in the car today – I love driving, I loved driving every minute today and I hope I have many more days to go."
A renewed challenge is expected from Ferrari who had the fastest car earlier in the season and their driver Sebastian Vettel – who fought Hamilton until a late slump ended his hopes of a fifth title. He was second in Abu Dhabi.
"It has been a very intense year and I think we have to look at ourselves, as there are many things that we can do better and the potential this team has is still huge," Vettel said.
The form driver of the last few races has arguably been young Dutchman Max Verstappen, who could push into the title battle for Red Bull.
"Everyone is ready for a bit of a break now, so we will take some time off once testing is complete, and come back refreshed and ready for a new challenge in 2019," he said after finishing third.
It was the final appearance, for now, for McLaren's Stoffel Vandoorne, Sauber's Macrus Ericsson, Sergey Sorotkin of Williams and Force India's Esteban Ocon as they don't have race seats for 2019. Toro Rosso's Brendon Hartley is also likely to bid farewell.
Kimi Raikkonen, Daniel Ricciardo, Charles Leclerc, Carlos Sainz, Pierre Gasly and likely Lance Stroll will all be back with different teams next year – Sauber, Renault, Ferrari, McLaren, Red Bull and Force India respectively.
Robert Kubica, Daniil Kvyat and Antonio Giovinazzi will return to F1 with Williams, Toro Rosso and Sauber, and there will be debuts for Lando Norris (McLaren) and George Russell (Williams).