John Ellis began his literary writing at day-school in Wine Office Court, Fleet Street, where he learned a rudimentary level of grammar and translated a Latin poem entitled "Marston Moore, sive de obsidione prœlioque Eboracensi carmen lib. 6" by Payne Fisher. His writing improved as his knowledge of Latin grew by following the lessons his master, John Taverner, a scrivener, gave to his son at Merchant Taylors' School.
Ellis continued to develop his literary writing by exchanging letters written in verse with a number of peers and colleagues. Initially, he primarily corresponded in verse with Rev. N. Fayting at Merchant Taylors' School. This verse style of correspondence endeared him to literary friends and intellectuals and led to some instances of publication.
In 1742-3, Ellis translated friend Dr. King of Oxford's "Templum Libertatis" into poetic verse. However, this translation was never printed. Some of Ellis' literary writing was published in 1767, when his poetic epistolary response to friend, Moses Mendez, on journeying to Ireland, was printed in a "Collection of Poems."
Ellis' most challenging work of translation was of "Ovid's Epistles," though this too was never published. Between 1720 and 1782, Ellis published a sparse number of poems and translations.
Ellis also wrote non-literary work as a scrivener, a position that required him to draw up deeds and charters concerning local tenements, which by law had to be sealed.