A hotel manager said the attacker was about to be served food in the Taprobane restaurant, which was packed with Easter guests, when his payload exploded.
A security official official said at least the two of the church blasts were carried out by suicide bombers.
Out of those killed, 35 were foreigners, news agency AFP reported quoting police.
A relative of a victim of the explosion at St Anthony's Shrine, Kochchikade church reacts at the police mortuary in Colombo, Sri Lanka.
Alex Agileson, who was in the vicinity, said buildings in the surrounding area shook with the blast.
Hospital sources also said Japanese citizens were among those injured by the bombs which ripped through high-end hotels and churches holding Easter services.
67 people were killed in St. Sebastian's church in the city of Negombo, north of Colombo.
St Sebastian's appealed for help on its Facebook page.
Embassies in Colombo warned their citizens to shelter in place, and Sri Lankan Airlines told customers to arrive at the airport four hours ahead of flights because of ramped-up security in the wake of the attacks. Police said another explosion was reported at a church in Batticaloa.
The places hit were Kochikade Church, Katuwapitiya Church, Shangri-La Hotel, Cinnamon Grand Hotel and a church in Batticaloa. "To see an attack in Sri Lanka while people were in churches and at hotels is devastating".
The Shangri-La Hotel in Colombo, which was the site of one of the explosions, released a statement, saying it was one of the several locations in Colombo which were affected by this morning's attacks.
An eight blast hit a house in Colombo.
Global Affairs Canada has issued a statement warning that the situation in the island nation remains "volatile", and more attacks are possible.
There was no immediate claim of responsibility.
Prime Minister Justin Trudeau joined other world leaders in expressing sorrow and shock at the attacks, while condemning the targeting of worshippers on Easter Sunday.
Prime Minister Ranil Wickremesinghe said he feared the violence could trigger instability in Sri Lanka, a country of about 21 million people, and he vowed the government will "vest all necessary powers with the defence forces" to take action against those responsible. "I call upon all Sri Lankans during this tragic time to remain united and strong", he said in a Tweet.
Although Christians form only around 7 per cent of the Sri Lanka's mainly Buddhist population, they are found both in the majority Sinhalese and minority Tamil communities.
This is a developing story and will be updated accordingly.