Finkley Down Farm, in Hampshire, posted a video of the hungry rodents munching on the Christmas dinner accompaniment.
The clip, which garnered 6m views in four days, prompted criticism from some who were concerned the vegetables could cause "fatal" bloating.
However, the farm and the RSPCA and Blue Cross animal charities said they were safe "in moderation".
Facebook user Bob Hammer commented : "These animals are doomed from bloat as a result of being able to eat this many Brussels, Finkley Down Farm you need to be taken to task!!"
Another user, Katie Jacqueline Crossingham, said: "Please be aware: Sprouts can cause bloat in guinea pigs, which can often lead to a nasty, painful death."
The farm, which posted the video as a festive message to its followers, said the welfare of its animals was "paramount" and added it had "expert livestock staff" to deal with the needs of individual animals.
"Here at Finkley we have a large herd of guinea pigs nearly 50 in total - the sprouts in the video are equivalent to one per guinea pig," the farm added.
"We are aware that Brussels sprouts can be difficult for guinea pigs to digest, however, these are safe for them to eat in moderation - something we keep a close eye on to ensure they aren't getting carried away."
An RSPCA spokeswoman described the video as "adorable".
"Sprouts can make a nice Christmas treat for guinea pigs and offering them as occasional treats in moderation can add variety and interest to their diet," she added.
Katie Stiles, animal welfare assistant at Blue Cross, said: "As part of a balanced diet they are absolutely fine.
"Guinea pigs need a mix of vegetables, as sprouts and cabbages can cause bloating - though this is more of an issue with rabbits - but they also need vegetables rich in vitamin C, such as peppers, as they are unable to produce it themselves."
A family farm provoked controversy when it posted a video of guinea pigs eating Brussels sprouts.