Tosista was born 1787 in Metsovo, Epirus, the first son of Constantinos Tositsa. He commenced his education in Metsovo, and continued in Thessaloniki where his father had a fur shop. He assisted his father, learned the trade of a furrier and, in 1806, took control of the business. In time, his brothers Theodoros, Constantinos and Nikolaos as well as his sister Stamatia (mother of Nikolao Stournaris) found employment and joined the business, which became known as: "Filli Tossizza" in Egypt and after Stournaris joined: "Filli Tossizza E Sturnari.
The trade was successful, and soon they opened branches in Livorno, Malta and Egypt. About 1820, Michael Tositsa, settled in Alexandria, Egypt, and the business there became the centre of the Tositsa Emporium.
His skills and interests made him a close friend and administrator of the properties of Mohammed Ali of Egypt. His involvement in agriculture and especially farming cotton made him one of the richest business man in Egypt. About 1832, he was appointed Ambassador of Greece in Alexandria.
His made contributions towards the Greek Revolution - supporting the Georgios Kountouriotis government financially - education (benefactor of the Tositsa school of Alexandria) and religion (benefactor of the Greek Church and Greek Cementry in Alexandria) and last but not least, benefactor of the Metsovio Polytechnio of Athens.
After the death of his nephew Stournaris, his health suffered a lot. He returned to Greece and settled in Athens where he died. In his will, he left money for the maintenance of various schools (Metsovo, Thessaloniki). He also, in memory of his nephew as well as on his own accord, made donations to various Greek institutions, like the University, Arsakio, public hospitals, orphanage and Polytechnio.
Michael Tositsa was married to Helen.
- Βιοι παραλληλοι, των επι της Αναγεννησεως της Ελλαδας διαπρεψαντων ανδρων, by Anastasios Goudas, Athens 1871, Vol D.