The German announced on Twitter that he is "excited to be working with Robert" on his "return to F1".
Rosberg was on the grid when the now 32-year-old last raced in F1 in 2010, but since retiring has been open to new opportunities within motor racing.
Sport Bild reports that Rosberg, also 32, will share responsibilities for the Pole's attempt to come back to F1 with Kubica's long-time manager Alessandro Alunni Bravi.
Kubica was hoping to return from his permanent injuries with Renault next year, but is now linked with a potential move to Williams for 2018.
"It's fantastic to work with Nico," he said. "We've known each other since childhood and he'll now be a big help with my Formula 1 comeback."
Kubica raced for BMW and Renault before he was forced to withdraw.