Numerous reports had Kenseth looking for a better deal with another team.
Kenseth, one of the sport's top drivers, was the NEXTEL Cup Series champion in 2003, has made the Chase for the Nextel Cup each of the past two years, has 10 wins, 51 top-five finishes and 99 top-10s in NASCAR's top division since 1999.
In 1995, Kenseth, a native of Cambridge, Wis., was the first rookie to win the Coca-Cola 600 at Concord, N.C., on Memorial Day.
"We are very pleased that Matt extended his contract," said Roush Racing owner Jack Roush. "It's very assuring knowing that he will be staying on with us and I know that the first goal on his agenda is to take that championship trophy back."