The 30-year-old appeared to confirm the move when interviewed by Colombian television station Caracol at the Vuelta a España. UAE Team Emirates confirmed to Cyclingnews that the deal was "advanced" but, having not prepared their own announcement, denied it had been finalised.
"It's my last year at Sky. I've already signed with UAE Emirates," Henao said.
Henao turned pro with Team Sky in 2012, having chosen to ignore contract offers a couple of years previously to continue his development in Colombia before making the move to Europe.
He finished ninth overall at the 2012 Giro d'Italia in what was his debut Grand Tour and supported Chris Froome to Tour de France victory in 2016 and 2017. His personal highlight in Sky colours came with victory at last year's Paris-Nice, while he has also won stages at the Vuelta al Pais Vasco and Tour de Pologne, as well as twice winning the Colombian national road race title.
He has endured difficult moments at Sky, too. He was twice sidelined - and later cleared - over biological passport issues, with the team investing in as-yet unpublished studies into his status as an 'altitude native'. He also suffered a career-threatening knee injury in 2014.
"I'm very grateful to this team for everything they've given me," Henao said. "I'm nostalgic to leave because I'm saying goodbye to great friends and great people."
Henao's younger cousin, Sebastian Henao, turned pro with Team Sky in 2014 and is also out of contract for next year, though it is unclear if he will follow him across to UAE.
While Filippo Ganna moves in the opposite direction, UAE have also recruited Tom Bohli from BMC along with three promising neo-pros in Alessandro Covi, Tour de l'Avenir winner Tadej Pogacar, and fellow Colombian Christian Muñoz.