The scandal erupted after some of the legislators posted selfies on social media of themselves enjoying matches in Russia.
"Isn't that a big bad joke, that leaders can travel all the way to Russia to watch football when we have a lot of problems here?" asked Sylvester Aseka, who sells second-hand computers in Nairobi.
"Oh my God, I want to believe that is not true, the pictures some of them are posting," said Jacinta Mong'ina, 26, a student. "It means they have a lot of time and resources to go to Russia. When will they serve their constituents?"
The Star daily newspaper reported that around 20 MPs had travelled to Russia at the beginning of the month and were expected to attend Sunday's final.
The cost of accommodation, per diems and match tickets was being footed by the government, it said.
The Star's estimate of the total cost was around $450,000 (385,000 euros). By comparison, the minimum wage in Kenya is between $120 and $280 per month, depending on the skill.
In parliament, National Assembly Speaker Justin Muturi confirmed the trip but said it was "not a bad thing".
"They must prepare a report when they come back and table it in parliament. That's the standard procedure," he said.
According to The Star, Senate Clerk Jeremiah Nyegenye also defended the trip as "official business".
"It is their responsibility to understand sports, how to host such international tournaments. This is not a holiday and it is too simplistic to look at it as a joyrider mission," he was cited as saying.
Kenya's Harambee Stars have never reached the World Cup finals, and have not qualified for any major international tournament since the 2004 Africa Cup of Nations.
Kenya's lawmakers -- among the highest paid in the world -- have often rubbed public opinion up the wrong way notably over their salary demands.
Last August, before they had even taken up their seats after an election, the new MPs launched a campaign to demand higher wages.
Kenya has also previously courted scandal at major sporting events, from doping allegations to the 2016 Olympics where several athletics officials were charged with offences such as stealing team uniforms.