Lendl, who coached Andy Murray during multiple Grand Slam victories, will replace Craig Boynton who parted ways with Hurkacz in August after five years together.
Massu, who won the men's singles and doubles gold medals in the 2004 Olympics, coached Dominic Thiem when he won the US Open in 2020.
"Having Nicolas Massu and Ivan Lendl as part of my team is an honour,” Hurkacz told the ATP website in a statement. "Their knowledge and dedication inspire me to work harder than ever, and I’m ready to put in the hard work."
Former Wimbledon semi-finalist Hurkacz achieved a career-high ranking of world number six in August, but struggled to regain form after an injury suffered during Wimbledon saw him undergo meniscus surgery in July.
"This has been a year of ups and downs; I’ve learned a lot and grown a lot, and I can finally say I am fully healthy and ready for the challenges ahead,” Hurkacz added.