In the academic year 1948/49 he attended in Faculty of Philosophy in Zagreb and graduated in 1953.

In the same year he was elected as assistant to the academy's Institute for Language, and in 1956 he performed the same duties at the Faculty of Philosophy at University in Zagreb in the Department for Dialectology and History of Croatian.

In 1977 he was elected to associate membership of the Croatian Academy of Science and Arts, and in 1986 he became a full member.

Since 1 January 2004 until 11 November 2010 he has been president of the Croatian Academy of Science and Arts.

Moguš was an editor in chief or co-author of many magazines and editions, like "Bulletin of the Institute for Linguistics of Faculty of Philosophy", "Bulletin scientifique", "Works of Institute for Slavic Philology", "Croatian Dialectology Collection", "Language", "Old Croatian Writers", "Works of Croatian Academy of Science and Arts", "Pauline Collection", "Senj Glagolitic circle 1248 - 1508", "Cithara octochorda".