Researchers found that mothers who attended group singing sessions with their babies took a lot less time to recover from their symptoms than those who didn't.
Published in the British Journal of Psychiatry, the study involved 134 women suffering from post-natal depression, which is estimated to affect one in eight new mothers.
The participants were split into three groups - one took part in group singing, a second took part in creative play sessions, and a third received their usual care (such as family support, mindfulness and antidepressants).
While all groups improved over ten weeks, the mothers in the first group - who attended singing workshops - reported a much faster improvement than the other women, with a 35 per cent decrease in depressive symptoms after six weeks.
At the singing workshops, mothers learnt lullabies and songs from around the world with their babies and created new songs about motherhood together.
The therapy could be a new way for mothers struggling with post-natal depression to tackle their symptoms as quickly as possible, as early recovery is seen as being key in limiting the effects on both mother and baby.
Dr Rosie Perkins, principal investigator on the study, said that even though the discovery was small, it could make a big difference.
'Post-natal depression is debilitating for mothers and their families, yet our research indicates that for some women something as accessible as singing with their baby could help to speed up recovery at one of the most vulnerable times of their lives', she said.
Lead author Dr Daisy Fancourt, from University College London, reinforced that idea: 'Many mothers have concerns about taking depression medication whilst breast-feeding and uptake of psychological therapies with new mothers is relatively low.
'So these results are really exciting as they suggest that something as simple as referring mothers to community activities could support their recovery.'