Odinga died on Wednesday while receiving medical treatment at a hospital in India.
In recent weeks, there has been speculation about his health, although family members and political allies had dismissed reports suggesting he was critically ill.
A political mobiliser and towering figure in Kenyan politics, Odinga ran unsuccessfully for the presidency five times. He rejected the results on each occasion, often saying that victory had been stolen from him.
He was vindicated by Kenya's highest court after the 2017 elections, when it annulled Uhuru Kenyatta's victory and ordered fresh polls. However, he boycotted the rerun, demanding electoral reforms.
He has often reconciled with the incumbent president after contentious elections.
After his most recent defeat in 2022, he later joined President William Ruto in a so-called broad-based government, which brought several of his allies into key positions.
He defended the move as necessary for national unity, coming in the aftermath of watershed nationwide protests last year that culminated in the storming of parliament. Dozens of protesters were killed in confrontations with security officers.
The Ruto administration backed Odinga's bid to become chairperson of the African Union Commission, in elections held earlier this year. Despite strong regional support, he lost to Djibouti's Mahmoud Ali Youssouf.
Odinga inspired a passionate and loyal following throughout his political career, especially in western Kenya, where he was from.
His supporters called him "Baba" (Father), "Agwambo" (Act of God), and "Tinga" (Tractor) - drawn from his party's symbol during the 1997 elections.
He was widely regarded as a master strategist and mass mobiliser, often drawing huge crowds to his political rallies, and he had a deep ability to connect with ordinary people.
He will be remembered for his unwavering fight for democratic freedoms and human rights.
He was a former political prisoner, and holds the record for being Kenya's longest-serving detainee. His struggle against one-party dictatorship saw him detained twice (from 1982 to 1988 and 1989 to 1991) during the rule of Daniel arap Moi.
He was initially imprisoned for trying to stage a coup in 1982, which propelled him on to the national stage.
