The 36-year-old helped to deliver Elia Viviani and Julian Alaphilippe to stage wins in the Tour de France this year and has played a key role in many of Deceuninck-Quickstep's 55 wins this season.
Before this season, Richeze also helped Gaviria to a pair of Tour de France stage wins in 2018 and four stages and the overall points classification in the 2017 Giro d'Italia. He's known as one of the best in the business, with an uncanny knack for threading his way through the charging peloton to deliver his sprinter to the front at just the right moment.
This season Gaviria has struggled with knee injuries and with finding success in the WorldTour. The Colombian has won just two WorldTour races - one stage each in the UAE Tour and Giro d'Italia - but has come second on six other occasions. Richeze could be the key to turning around that ratio.
"Over the years, Richeze becomes increasingly important for the teams where he rides, he possesses the perfect mix of skill and strength on the bike with experience and intelligence," UAE Team Emirates manager Joxean Matxin said.
"I have no doubts when I say that he is the best lead-out man in the world, and will slot into our sprint train as the last man for Gaviria, as the pair are well used to working together already."
Richeze said that reuniting with Gaviria and changing teams so late in his career was a 'great motivation'.
"Gaviria is more than a teammate, he is a great friend and I'm really looking forward to working together again with him," Richeze said, adding that becoming a mentor to the team's young riders is another motivator.
"I am very happy to be able to work with many of the people I have worked with in the past but also to be able to support young talents who are looking for their first successes."
It's another blow for Deceuninck-Quickstep, who have lost Elia Viviani and another lead-out man Fabio Sabatini to Cofidis, Enric Mas to Movistar and Davide Martinelli to Astana.
UAE Team Emirates bolstered their time trial power base by signing U23 champion Mikkel Bjerg and former junior world champion Brandon McNulty.