Mind Candy is aiming to raise £100,000 for BBC Children in Need - pledging its support to a number of initiatives.
To kick off the activity, Pudsey recently visited Moshi HQ and featured alongside favourite characters Katsuma and Poppet in a special broadcast due to be aired on CBBC's Newsround this week.
The BBC Children in Need mascot, Pudsey has been made available to be bought in game on MoshiMonsters.com. If one million Pudseys are purchased with players' in-game currency (Rox), then the Moshi Foundation - which was set up by Mind Candy in 2011 - will donate £10,000 to the cause.
In addition, Mind Candy and Vivid have pledged a further £90,000 to BBC Children in Need and have created 30,000 limited edition Spotty Moshlings Collector Tins. These will go on sale in October, with £3 of each sale going to the charity fundraiser.
"BBC Children in Need does a fantastic job," said Michael Acton Smith, CEO of Mind Candy. "Everyone here at Moshi Monsters is delighted to help them and hopefully we will raise lots of money to support disadvantaged children and young people."