Both candidates had initially pulled out of the final debate, but after a change in format Odinga agreed to take part.
Both candidates had initially pulled out of the final debate, but after a change in format Odinga agreed to take part and the moderators were left in suspense until the last minute over whether or not Kenyatta would show up.
This gave veteran opposition politician Odinga 90 minutes to field questions about his policies, attack Kenyatta's government and defend his record during his time as prime minister in a power-sharing government after disputed 2007 polls.
The solo debate comes as several pre-election polls show an extremely tight race between the historical rivals, and it was unclear if the lack of a proper presidential debate would sway voters.
Kenyatta "owed the country a duty to appear, a duty to account for his five years," said Miguna Miguna, a former advisor to Odinga and independent candidate for Nairobi governor, as part of the post-debate analysis.
"I think it was a mistake of monumental proportions. It was a miscalculation, a deliberate or naive misunderstanding of what the president means."
Other analysts said it was an "anti-climax" and agreed it was a boost for Odinga.
An official in Kenyatta's campaign team said: "We don't see value in this thing, it's a debate that will not translate to votes on August 8."
Kenya held its first ever televised presidential debate in 2013, which included both Kenyatta and Odinga. Afterwards, Kenyatta complained that he had been unfairly targeted by moderators.
Odinga is leading a rare coalition of opposition heavyweights, the National Super Alliance (NASA) in his fourth bid to be president.
"I lost once," he said as the audience laughed, in reference to his claim that elections in 2007 and 2013 were stolen from him.
Many observers agree with Odinga's view that the 2007 election was stolen from him, triggering widespread politically-motivated tribal violence which left more than 1,100 dead.
The violence of 2007 looms over Kenya's politics a decade on, and Odinga has already repeatedly claimed there are plans afoot to rig the election.
Another analyst on the post-debate panel said that seeing the two contenders on the same stage discussing issues could have reduced tensions ahead of the vote.