At a state dinner on Tuesday, Charles expressed his "deepest regret" for what he called abhorrent and unjustifiable acts of violence committed against Kenyans during the country's independence struggle.
President William Ruto commended the British monarch's first step toward going beyond the "tentative and equivocal half-measures of past years", but said much remained to be done.
During the 1952-1960 Mau Mau revolt in central Kenya, a period known as "the emergency", some 90,000 Kenyans were killed or maimed and 160,000 detained, with many subjected to torture, according to the Kenya Human Rights Commission (KHRC).
British colonialists also committed gross human rights violations, including land expropriation, killings, and sexual violence, against hundreds of thousands of people in western Kenya over decades, United Nations investigators have said.
The King on Wednesday afternoon listened to accounts of that violence by relatives and representatives of those involved in the struggle, Buckingham Palace said in a statement without providing further details.
Ambrose Tarus, great-grandson of King Koitalel Arap Samoei, who led a decade-long rebellion by the Nandi people before he was killed by a British colonel in 1905, said the meeting was cordial, and that he appreciated the chance to explain the injustices against his ancestors.
Charles' banquet speech was a good starting point, Tarus said: "He seems to understand what the problem was, and that's progress for me... and going forward I am hopeful it will bear good fruits."
Britain agreed to a £20 million ($NZ41.5 million) out-of-court settlement in 2013 to more than 5200 survivors of abuses during the emergency, but it has refused to issue an apology and has rebuffed claims by other communities.
Britain's high commissioner to Kenya, Neil Wigan, told a local radio station last week that an apology would take his country into "difficult legal territory".
"His expression of regret, without apologising, means he is still holding back," Gideon Mungai, a former Mau Mau fighter, said about Charles' remarks. "What would make me even happier in my old age is the return of the grabbed land."
UNDER PRESSURE
Paul Muite, a senior Kenyan lawyer who represented Mau Mau veterans in the 2013 case, said there were more than 2000 additional victims of abuses during the emergency who did not receive compensation in that settlement.
Charles' visit, his first as monarch to a former colony, comes at a time when Britain is under pressure to do more to recognise colonial-era abuses. Some, notably Barbados and Jamaica, have been re-evaluating their ties to the monarchy.
David Ngasura, a historian from the Talai clan in western Kenya, whose members were forced from their land in the 1930s and sent to detention camps, said Charles' acknowledgment of colonial-era crimes was "not enough".
On Wednesday morning, Charles and Camilla visited a cemetery for veterans of World War 2. They awarded four veterans, who fought alongside the British, medals to replace ones they had disposed of during the Mau Mau uprising.
Charles later addressed staff at a United Nations office about climate change before flagging off a "Run for Nature" race in the capital Nairobi's Karura Forest alongside Eliud Kipchoge, one of the fastest marathon runners in history.
