The Australian is a graduate of Red Bull's driver development scheme, breaking into F1 with a part-season with the now-defunct HRT squad funded by the fizzy drink firm in 2011. He then spent two years at Toro Rosso – Red Bull's junior team – before gaining promotion to the top squad.
Ricciardo, 29, finished third in the world championship in 2014 and 2016, and is currently fifth in this year's standings, with two wins so far this season.
Renault returned to the sport as a full works team in 2016, and has yet to score a podium. Ricciardo will join Nico Hulkenberg at the French squad, replacing Carlos Sainz.
Ricciardo described the move as “one of the most difficult decisions to take in my career so far.”
He added: “I thought that it was time for me to take on a fresh and new challenge. I realise that there is a lot ahead in order to allow Renault to reach their target of competing at the highest level but I have been impressed by their progression in only two years, and I know that each time Renault has been in the sport they eventually won.”
Cyril Abiteboul, Renault Sport Racing’s managing director, added: “Daniel’s signing underscores our determination to accelerate our progress towards the forefront of the sport. It is also a recognition of the work accomplished over the past two and a half seasons. Daniel’s undoubted talent and charisma are a huge bonus and statement for the team. We will have to repay his faith in us by delivering the best car possible. We welcome him to our growing team in 2019 with a great deal of pride, but also humility.”