He was the third but eldest surviving son and heir of Sir Ralph Russell (1319–1375) and his wife Alice (died 1388).
He held the post of Sheriff of Gloucestershire four times, and was Coroner and Justice of the Peace, Tax Collector and Commissioner of Enquiry.
He was descended from an ancient line which can be traced back to 1210, which ended on the death of his son Thomas, from his second marriage, as a young man without male issue.
He was granted in wardship to Sir Robert Assheton (died 1384), his father's cousin, soon to be appointed Treasurer of the Exchequer.
Having reached his majority, in December 1377, Maurice took possession of his inheritance, following the early deaths of his two elder brothers, Theobald and John excepting the customary 1/3 dower share retained by his mother Alice, who died on 16 March 1388.
In 1382, Maurice leased the reversion of Kingston Russell, due him on his mother's death, to Walter Clopton for 20 marks p.a.
Assheton's manor of Litton and Combe in Dorset were split, after some argument, between Russell and Sir Ralph Cheyne (died 1400), of Brooke in Westbury, Wilts., whose father, Sir William Cheyne, of Poyntington, Somerset, had married, as his second wife, Joan Gorges, the youngest daughter of the 1st Baron Gorges.
His estates in Hampshire, Somerset, and Gloucesterhire were then said to be severally worth £40 p.a., whilst those in Dorset apparently gave him an annual income of £122 5s, making a total, no doubt under-declared, of over £242.
In 1408, he was involved in a dispute, of unknown cause, with the influential Sir Walter Hungerford, as a result of which both men were required to enter into recognizances for 1,000 marks each as surety that they would abide by the award of the Chancellor Thomas Arundel, Archbishop of Canterbury.