Kenya Power in their latest update on the issue said teams from the company were working to restore power to the rest of the areas.
"We are pleased to report that power has been restored to most parts of North Rift, Central Rift, Western Kenya, South Nyanza and sections of Nairobi and Mt Kenya regions following a widespread outage," the statement issued on Wednesday morning said.
"Our team is diligently working to restore supply to all the remaining areas," it said.
In an update issued at 1.28 am, the utility company confirmed there was a widespread power outage affecting most of the country except parts of the western and North Rift regions.
As at 5 am, power had been restored in most parts of the country, but some Kenyans, especially in Nairobi woke up in darkness.
The utility company said the cause of the Monday night outage had not been determined.
"We regret any inconvenience this may have caused and request our customers to be patient as we work towards restoring normalcy at the earliest opportunity," it said.
Kenya Power said it will provide timely updates on the progress of the restoration process.