The split comes on the heels of Raducanu's second-round exit at the Australian Open, where the 23-year-old fell 7-6(3), 6-2 to unseeded Anastasia Potapova.
Raducanu had appointed the Spaniard on a full-time basis in August, bringing in a coach with a strong Grand Slam pedigree.
Roig served as a long-time member of Rafael Nadal's coaching team during much of the 22-time major winner's career.
"While we have come to the conclusion together that we ought not to move forward, please know that I am very grateful for all you have taught me ...," Raducanu posted on Instagram.
Roig was the eighth coach of Raducanu's career, as the carousel continues to spin for the Briton.
She has struggled to find stability in her team since her stunning breakthrough at Flushing Meadows.