"Mike is a talented veteran center who has produced offensively everywhere he has played," said Predators GM David Poile. "We have done our due diligence and believe Mike has a lot to offer to our team, improves us at our center ice position and will fit in with our group and contribute."
Ribeiro, 34, has amassed 202 goals and 454 assists for 656 points in 865 career NHL games with Montreal, Dallas, Washington and Phoenix.
In 2013-14, he registered 16 goals and 31 assists for 47 points.
Ribeiro was originally drafted by the Canadiens in the second-round, 45th overall, of the 1998 NHL Entry Draft.
Roy, 31, picked up nine goals and 28 assists for 37 points in 75 games with the St. Louis Blues last season.
"Derek brings us added depth, playmaking ability and experience at center, helping complement our young, developing wingers," Poile said. "He has played in a number of roles, averaging about 19 minutes of ice time throughout his career, and is effective on the power play. He provides our coaching staff with some added skill and maturity down the middle when putting together our lineup for the coming season."
The Ottawa native has accumulated 177 goals and 315 assists for 492 points in 666 career NHL regular-season games with Buffalo, Dallas, Vancouver and St. Louis.
Roy was originally selected by the sabers in the second-round, 32nd overall, of the 2001 NHL Entry Draft.