Abstract Samuel Beckett, the Irish author and playwright was born in 1906 in County Dublin, Ireland and died in 1989, in Paris, France. From 1929 to 1989, Beckett wrote letters through which his life is depicted. His letters were published in the form of four volumes entitled as follows: volume I: 1929-1940 (published in 2009), volume II: 1941-1956 (published in 2011), volume III: 1957-1965 (published in 2014), and lastly, volume IV: 1966-1989 (published in 2016). These letters were later translated in French by the publishing house of Gallimard between 2014 and 2018. Within a morpho-semantic framework of analysis, one may wonder to what extent there exists stylistic affinities between his letters and his famous tragicomedy entitled Waiting for Godot (published in 1952). In other terms, are there constant, and/or shared stylistic units? To what extent has the register been changed from his letters to his play? How may the vocabulary, punctuation, and grammar differ from the English version of Waiting for Godot to the French version? Do these stylistic changes from English to French affect the notions of 20th-century man in the society in France? By drawing on certain theories of theoreticians in linguistics and translation studies such as Brian T. Fitch, Anthony Uhlmann, and Saeid Rahipour, this research seeks to present a linguistic and translation analysis of Beckett’s register in his four volumes of letters and English, and French versions of his play Waiting for Godot. Hence, this study aims to investigate the extent to which the Irish writer’s register has been differentiated in the corpus under study by the passage of time to suit the stylistic norms of 20th century in France and England.