Schumacher received the news that had long been expected on Thursday when it was announced his current contract with the American team would not be extended.
Haas have instead opted for experience and brought Nico Hulkenberg back to the sport after a three-year absence.
For Magnussen, it means a reunion with a man he once told to "suck my balls" but before that new partnership begins, the Dane has been looking back at the time he spent alongside Schumacher.
"It's a double-sided thing, right?" Magnussen said, as reported by Motorsport.com. "On one hand, it's exciting getting someone like Nico in with all his experience and capabilities.
"And, on the other hand, I feel bad for Mick, because I know how that feels. And I've been in that situation myself."
Magnussen spent a year out of the sport having been replaced at Haas by Nikita Mazepin but was brought back weeks before the start of the 2022 season following Russia's invasion of Ukraine and the effect that had on Mazepin's position.
"I think he's [Schumacher] done a good job this year, I like him as a person as well. It's easy to feel bad for him.
"F1 is tough, but it's also possible to make it back. I've done that twice. I hope he can keep fighting and try to make it back on the grid."
Magnussen went on to say he thought Schumacher deserved a spot on the grid and that he needed to "hang in there."
"But I also feel that when I'm patting him on the shoulder saying, 'keep at it', then it also has some weight," the 30-year-old said.
"I've come back twice to the sport. I've shown that nobody knows what is going to happen; you can never say never in the sport. So you need to hang in there.
"I like Mick and I think he deserves a spot on the grid. All I can say is, I hope the best for him and I believe that there is a way back to F1 for him."
Schumacher's options for remaining on the grid in 2023 appear limited with every seat all but confirmed. The only seat that remains a possible option is the one of Williams with the team having to wait for the F2 result of their preferred choice in Logan Sargeant and his search for a Super Licence.