Văcărescu wrote one of the first printed books on Romanian grammar in 1787, an edition which also included a section dedicated to the study of prosody; it was titled Observaţii sau băgări de seamă asupra regulilor şi orânduielilor gramaticii româneşti ("Observations or Reckonings on the Rules and Dispositions of Romanian Grammar"). He also completed a work on Greek grammar (Gramatica greacă completă).
Văcărescu's lyrical works take inspiration from both Anacreon and folklore, and center on romantic love. The best-known poems he left behind are Amărâta turturea ("Embittered Turtle Dove") and the minuscule Într-o grădină ("In a Garden"). Aside from these, he was also the author of a Istorie a Preaputernicilor Împăraţi Otomani ("History of the All Mighty Ottoman Emperors").
On several occasions, Ienăchiţă Văcărescu served Wallachia as a diplomat in missions abroad, including negotiations carried out in the Habsburg realms for the sons of Prince Alexander Ypsilantis to return after their 1782 flight to Vienna; he met and conversed with Emperor Joseph II, and also befriended the French ambassador, Baron de Breteuil. His impressive knowledge of Italian was the subject of a 1929 study by historian Nicolae Iorga, De unde a învăţat italieneşte Ienăchiţă Văcărescu ("Where Has Ienăchiţă Văcărescu Learned His Italian From?").