Hamilton has put pen to paper on a three-year deal with Mercedes after failing to negotiate a new contract at McLaren, who have replaced the Brit with Sauber driver Sergio Perez.
"I have had three nice years with the team which unfortunately did not go as well as we all would have wanted on the sporting side," said Schumacher.
"I wish Lewis well and for the team to achieve the success we worked so hard for in the build-up. I would like to thank the team for their trust and all the guys for their unconditional commitment. I will now concentrate on the next races."
There has been no confirmation that the 43-year-old is planning to retire at the end of the season.