Massillon soon gained a wide reputation as a preacher and was selected to be the Advent preacher at the court of Versailles in 1699. He was made Bishop of Clermont in 1717, and two years later was elected a member of the Académie française. The last years of his life were spent in the faithful discharge of his episcopal duties; his death took place at Clermont on September 18, 1742. Massillon enjoyed in the 18th century a reputation equal to that of Jacques-Bénigne Bossuet and of Louis Bourdaloue, and was much praised for his eloquence by Voltaire, D'Alembert and kindred spirits among the Encyclopaedists.
Massillon's popularity was probably because in his sermons he lays little stress on dogmatic questions, but treats generally of moral subjects, in which the secrets of the human heart and the processes of man's reason are described with poetical feeling. He has usually been contrasted with his predecessor Bourdaloue, the latter having the credit of vigorous denunciation, Massillon that of gentle persuasiveness. Besides the Petit Carême, a sermon which he delivered before the young King Louis XV of France in 1718, his sermons on the Prodigal Son, on the small number of the elect, on death, for Christmas Day, and for the Fourth Sunday in Advent, may be perhaps cited as his masterpieces. His funeral oration on King Louis XIV of France is only noted now for the opening sentence: "Dieu seul est grand." (Only God is great.) But, in truth, Massillon is singularly free from inequality. His great literary power, his reputation for benevolence, and his known toleration and dislike of doctrinal disputes caused him to be much more favourably regarded than most churchmen by the philosophers of the 18th century.
The first edition of Massillon's complete works was published by his nephew, also an Oratorian (Paris, 1745–1748), and upon this, in the absence of manuscripts, succeeding reprints were based. The best modern edition is that of the Abbé Blampignon (Paris, 1865–1868, 4 vols.; new ed. 1886).