Several properties in Mathare North were on Sunday morning destroyed by rowdy youths who said they were unhappy with the Supreme Court ruling that upheld the election of Uhuru Kenyatta as Kenya's fourth president.
A storeyed building and several business premises were burnt as the youth engaged in looting.
Police arrived at the scene and managed to contain the situation.
"We want Uhuru to know that we are not happy with the court ruling," they said.
Cord's presidential candidate Raila Odinga had challenged the result of the March 4 poll hoping for a rerun but while he begrudgingly accepted the Supreme Court's decision on Saturday, youths in his strongholds were enraged.
Riots broke out immediately after the ruling, leaving two dead and seven wounded in the city of Kisumu, Joseph Ole Tito, police chief for the western Nyanza region, said.
Many shops remained boarded up Sunday, their owners fearing fresh looting. There were few cars on the roads with residents preferring to walk to church after several vehicles were damaged Saturday by stone-throwing youths.
"In Kisumu ... the situation has been contained and business is resuming to normal," Kenya's police chief David Kimaiyo told AFP.
"We have an adequate number of police officers in all parts of the country including in those troubled areas," he said.
The gunshots that had rung out sporadically for much of Saturday evening in Kisumu died down around midnight, residents said.
There were no reports of casualties in Nairobi where Odinga supporters had lit bonfires and tried to block roads in some slum areas on Saturday.
"There were confrontations in Kibera and Mathare but we were able to contain the situation and we have sent more officers there," Nairobi police chief Benson Kibui said.
The six judges of Kenya's top court dashed Odinga's last hopes of victory by unanimously ruling that the March 4 election had been fair and credible and that Kenyatta and his running mate had been "validly elected".
The ruling paves the way for Kenyatta, the son of Kenya's first president and one of Africa's richest men, to be sworn in as head of state on April 9.
Odinga, who argued that the ballot had been marred by widespread irregularities, said he accepted the court's ruling and wished his rival well.
"The court has now spoken," Odinga said, adding that while he might not agree with all its decisions his faith in the constitution "remains supreme".
The announcement of his defeat in the last elections in 2007, when he ran against the now outgoing president Mwai Kibaki, led to Kenya's worst violence since Independence, with more than 1,100 dead and several hundred thousand forced to flee their homes.
Kenyatta for his part thanked his rival and said the court ruling was "a victory for all the Kenyans" who turned out to vote on March 4.
The White House, Britain, France and the European Commission all congratulated Kenyatta on his victory.
Kenyatta and his deputy William Ruto both face trial at the International Criminal Court in The Hague for crimes against humanity over their alleged role in planning the 2007-2008 post-election violence.
Official results showed the president-elect won 50.07 percent of the votes -- just making it over the 50-percent threshold needed to avoid a second-round ballot by some 8,000 votes.
Kenyatta will become only the second sitting head of state, after Sudan's Omar al-Beshir, to face charges at the ICC.
Analysts have argued that, far from being a handicap, the international court case helped him by providing his camp with a victimisation narrative and keeping the campaign's focus away from his rivals.