That is 10.3 million messages in 140-characters or less sent out over a 1.5-hour period.
The popular social micro blogging website said it is the most tweeted event in recent US political history, beating out any of the 2012 convention speeches, the 'ABC News' reported.
Twitter has also released a graph, which shows the most popular moments in the debate, according to the number of tweets per minute, or TPM.
According to the report, beyond the sheer volume of information and humour, there was genuine discussion happening on the social platform.
While some voiced their frustration with a particular candidate, others remarked on the style of the debate, the report said.
As the debate amounted to more than 10 million tweets, each on its own represents the impact of social media on this election: Every one of those tweets gave someone a public voice, it said.