Mary Richey was born in Cookstown, County Tyrone, Ireland.

At NAG in early 1926 the artist began exhibiting, and followed this with entries to the winter exhibition. She first exhibited in 1927 in St Ives, whilst using an Edinburgh exhibiting address. She is believed to have studied under Dod PROCTER for a while. In around 1930 Mary moved to Polperro, and was based in the village for around six years. She was invited to exhibit with the shortlived Polperro Arts Society, despite having moved to St Ives. She had became an active member of STISA in 1932.

By the time of her 1936 RA success she had again moved, this time to Bridport in Dorset. Subsequently she spent a few years in Italy, after which she did not exhibit as much. She died aged 62 in Edinburgh, where her brother and sister were living.