Top Gear's Boliva special was iPlayer's most popular TV programme, while day two of the England vs South Africa Test Match was the most popular radio programme.
Meanwhile, Eastenders, Doctor Who and Gavin & Stacey all featured in the top 20 most popular TV programmes.
Eastenders was among the top 20 most popular programmes on the BBC iPlayer during December 2009
The BBC also revealed the week of December 28 saw a record 17.3 million requests for TV programmes alone.
Furthermore, one in eight of the programme download requests came from either a Nintendo Wii or a Sony PS3 console, which are just two of the 20 different platforms the catch-up TV service is available on.
Catch-up service reviews:
"Breaking the 100 million barrier is a great way to kick off 2010 and these figures show that by offering simple and varied access to BBC iPlayer people are really finding it easy to catch up with their favourite programmes at a time that suits them," said Erik Huggers, director of future media and technology.
"I expect more people to start using the service as we continue to make it more widely available and I'm looking forward to some of the new innovations we have coming to the service later on in the year."