Marafa Hamidou Yaya, a former cabinet minister and aide to President Paul Biya, was sentenced after a brief trial, Africa Review reported.
Yaya has accused the government of carrying out a political prosecution against him. Yaya was at one point considered a possible successor to the 79-year-old Biya but was forced out of the cabinet in a 2011 reshuffle.
Yaya was convicted by Mfoundi High Court in the capital, Yaounde, of taking $29 million that was to be used for a new Boeing jet ordered by the president. Officials instead leased a used jet, nicknamed "the Albatross," that has had persistent problems.
Yves Michel Fotso, former president of the national airline, Camair, which has gone out of business, will also serve 25 years.
Five other defendants, three of them tried in absentia, have been sentenced to 10 or 15 years each, while a former prime minister, Chief Ephraim Inoni, is awaiting trial.