Mr Odinga made the declaration on Tuesday moments before police used teargas to stop him and his supporters from marching to Jacaranda grounds in Embakasi, Nairobi, for a prayer rally.
The swearing-in, he said, will be based on the results of August 8 presidential election, which he claims he won but was rigged out through manipulation of figures.
The inauguration, Mr Odinga, will be like that of new Zimbabwe President Emmerson Mnangagwa and not Kizza Besigye of Uganda.
Kenya opposition National Super Alliance (Nasa) leader Raila Odinga now says, like President Uhuru Kenyatta, he will also be sworn in as "the people’s president".
He made the declaration on Tuesday moments before police used teargas to stop him and his supporters from marching to Jacaranda grounds in Embakasi, Nairobi, for a prayer rally.
Mr Odinga said he will take oath of office on December 12 using Chapter 1 of the Constitution, which states that sovereign power belongs to the people.
"I am not a coward, I will be sworn as president on Jamhuri Day, I am the legitimate president," he told his supporters, who defied police operation to listen to him, during a stop-over on Manyanja Road, in Nairobi's Eastlands.
The swearing-in, he said, will be based on the results of August 8 presidential election, which he claims he won but was rigged out through manipulation of figures.
“Server indicated that we had 8.8 million votes while Kenyatta had 7.1million votes,” he said.
He reiterated his vow not to recognise President Kenyatta and his government despite being sworn in on Tuesday.
“We went to the courts and they said Kenyatta was not duly elected… They ordered IEBC to open servers but they refused because they knew all the secrets were there.”
The inauguration, Mr Odinga, will be like that of new Zimbabwe President Emmerson Mnangagwa and not Kizza Besigye of Uganda.
Mr Besigye, President Yoweri Museveni’s doctor-and-friend-turned-foe, has become the symbol of police repression and brutality in Uganda.
“Our first resolution is that we don't recognise Kenyatta as president,” Mr Odinga said.