The figures include a record number of visits to the newly updated OnTheMarket.com iOS and Android apps.
January also saw the portal’s highest ever number of visits from its property alert emails and a record number of leads provided to agents.
It was also a record month for the recruitment of contracted offices since January last year, in the run-up towards OTM’s launch at the end of that month.
Ian Springett, chief executive of OTM, said: “January proved to be a fantastic month for us in many ways.
“The website marked its first birthday in style, smashing its previous record of monthly traffic of 5.7m visits – achieved in October.
“More property-seekers also used the newly updated apps than ever before.
“Many people said OnTheMarket would not reach its first birthday but instead it has proved that it is thriving and is continuing to grow in every way and we look forward to welcoming more and more agents throughout 2016.”