The German joined the Milton Keynes-based squad ahead of the 2009 season and the combination has been the dominant force in Formula One ever since, with Vettel claiming four consecutive world championship crowns, 38 Grand Prix victories, and 44 poles over the past six seasons.
Red Bull also confirmed that Daniil Kvyat, who has impressed for sister team Toro Rosso during his rookie season this year, will be promoted to the main team alongside Daniel Ricciardo in 2015.
"Sebastian Vettel has advised us that he will be leaving Infiniti Red Bull Racing at the end of the 2014 season," a statement from Red Bull read.
We want to warmly thank Sebastian for the incredible role he has played at Infiniti Red Bull Racing for the last six years.
"As we wish Sebastian well in the next stage of his career, we also look to the future with excitement, as the vacancy makes way for the next generation of Red Bull racers.
"The Red Bull Junior Programme has developed some proven talents in recent times, including Sebastian Vettel and Daniel Ricciardo, who has excelled in the RB10 and become a three-time Formula One race winner in his first season with the team.
"We're pleased to announce that Daniel will be joined in the team for 2015 by another rising star from the Junior Programme, Daniil Kvyat."
Red Bull team principal Christian Horner added: "I think [Vettel] reached a stage in his career where he fancied a new challenge, so that's his prerogative and like in any relationship, if someone's heart is not in it, then it's time to move on.
"It's the end of a cycle of course, but it's also the start of a new cycle: Daniel [Ricciardo] is doing a great job this year and has got three wins already he shows the new strength we have coming through and we're excited about the prospect of Kvyat lining up with him. They're the next generation."
Vettel is expected to announce his future plans shortly.
His departure has massive significance in terms of the driver market. The 27-year-old has been widely tipped to move to Ferrari, with Fernando Alonso strongly linked with a switch back to McLaren.
Kvyat's promotion, meanwhile, means a seat will open up at Toro Rosso next year. Rookie Max Verstappen is already confirmed with the team for 2015.