He wrote an account of the failed siege of Constantinople by the Ottomans under the sultan Murad II in 1422. Cananus attributes the survival of the Byzantine capital to the miraculous intervention of Theotokos. The account differs from the contemporary history of John Anagnostes, who described Murad's sack of Thessalonica in 1430, chiefly in Cananus' frequent religious polemic, and in his willingness to write in the vernacular Greek, as opposed to the Atticism of Anagnostes and Critobulus. Their use of Greek, while "artificial in the extreme," is intended as an "imitation of the classics;" an ideal which had been "the governing principle for all writers who aimed at a good style not merely under the Roman empire but right to the end of the Byzantine period."
John Cananus is sometimes identified with Lascaris Cananus, who travelled to Scandinavia and Iceland around 1439: "Laskaris Kananos (ca. 1438–1439) has paid attention to coinage in Stockholm and Bergen, the subordination of Sweden and Norway to the Danish king, to the residence of the King of Denmark in “Kupanava”, Copenhagen, the supervision of the cities of Riga and Revel in Livonia by the archbishop and Great Master of the Order, etc. In his description of his voyage to Iceland Laskaris Kananos identified this island with the above-mentioned Thule, the inhabitants of which he calls “ichthyophags”, i.e. fish-eaters. This Byzantine traveller visited — penetrating into Venedicos Kolpos, i.e. the Baltic Sea — Norway, Sweden, Livonia, Prussia, Pommern, Schleswig, Denmark and Britain, whereafter he made a trip to Iceland." 
- Greek ed., with Latin translation, published with Sphrantzes in Corpus Scriptorum Historiae Byzantinae, 1838, p. 457-479. (Immanuel Bekker, ed.) View online.
- Greek ed., with Latin translation by L. Allatius, published in Patrologia Graeca, vol. 156. (Migne, J.P., ed.) View online.
- Lascaris Cananus: Lundström, Vilhelm (ed.) (1902) Laskaris Kananos. Reseanteckningar från de nordiska länderna. Utgifna och kommenterade av Vilh. Lundström. Upsala; Leipzig: Lundequist (Smärre Byzantinska skrifter; 1). (With Swedish Translation) https://archive.org/details/LaskarisKananosReseanteckningarFrnDeNordiskaLnderna
- Lascaris Cananus: Jerker Blomqvist 2002. The Geography of the Baltic in Greek Eyes. In Noctes Atticae: 34 articles on Graeco-Roman antiquity and its Nachleben. 36-51. Copenhagen: Museum Tusculanum. https://books.google.com/books?id=y37hozj-PeIC&lpg=PA36&ots=pfQIF49Ztb&dq=iceland%20kananos&pg=PA38#v=onepage&q=iceland%20kananos&f=false
- Online translation into Russian via German: Georg Jakob. Arabische Berichte von Gesandten an germanische Furstenhofe aus dem 9. und 10. Jahrhundert. Berlin 1927, pp. 46–47. http://vostlit.by.ru/Texts/rus8/Kananos/text.htm
- Online translation into Russian: А. А. Васильев. Ласкарь Канан, византийский путешественник XV века по Северной Европе и в Исландию. Харьков, 1914. pp. 3–8. http://miriobiblion.narod.ru/kananos/kananos.html
- Online translation into English: http://hellenisteukontos.blogspot.com/2009/09/lascaris-cananus-updated.html
- Harris, Jonathan (2010), ‘When did Laskaris Kananos travel in the Baltic lands?’, Byzantion 80, pp. 173–87 View online
- Smith, William (1870) Dictionary of Greek and Roman Biography and Mythology View online.
- Vasiliev, A.A. (1952). History of the Byzantine Empire, 324-1453. Madison: University of Wisconsin Press. p. 350 View online.
- Reynolds, L. D., & Wilson, N. G. (1991). Scribes and scholars: a guide to the transmission of Greek and Latin literature. Oxford: Clarendon Press. ISBN 0-19-872145-5. p. 46, 47
- Mikhail Bibikov: Byzantine sources for the history of Balticum and Scandinavia. Byzantino-Nordica 2004. http://www.fl.ut.ee/orb.aw/class=file/action=preview/id=381724/MST2-2005.pdf