He married Anne, daughter of Bolton Waller, of Shannon Grove and Castletown on 15 January 1835. Their eldest son, Thomas, died on the way to the Crimean War in 1855, aged 18, in a shipwreck off Italy; their eldest daughter Elizabeth Isabella died in Torquay at the age of 28 in 1861. Another daughter, Jane Diana, married the Rev. C. W. Furse in 1859. Through his son William Thomas Monsell, a magistrate and inspector of facturers, Monsell was grandfather to the artist Elinor Darwin (née Monsell).