After studying Secondary Education, he studied Philosophy and Arts at Santiago de Compostela University, taking a degree in Geography and History in 1974 with the minor thesis Notas sobre el arte en Baio (Soneira) y sus entornos. In 1991, he presented his doctoral thesis A arte relixiosa no arciprestado de Soneira. From 1979 to 1992, he worked as a teacher at 'Marqués de Suanzes' (Ferrol) and 'Antón Losada Diéguez' (A Estrada) Secondary Schools. During the school year 1991-92, he worked as an assistant lecturer in the Department of Art History at Santiago University. Since 1992, he has been a Professor of Geography and History. Nowadays, he is working at 'Antón Losada Diéguez' Secondary School in A Estrada (Pontevedra).
Xosé Mª Lema is the author of an extensive work and many articles on history, art history, ethnography, linguistic, onomastics, etc. These are some of his most outstanding books: Bamiro: un estudio do hábitat rural galego (1977), Lúa Nova-5 (1980), Lingua Galega-1º FP-1 (1982), Lingua Galega-FP 1º grao (1985), Historia do C.D. Baio e da Liga da Costa (1989), A Arte Relixiosa no arciprestado de Soneira (desde o 1500) (1992), A Arte Relixiosa na Terra de Soneira (1993, 1ª edición), Enrique Labarta Pose. Contos (1995), Un novo documento de Don Juan Antonio Posse: a 'Plática Tercera' (1838) (1998), O castelo de Vimianzo e os Moscoso de Altamira (1998), Arquitectura megalítica na Costa da Morte (antas e mámoas) (1999), Os mellores pazos da Costa da Morte (2001), Os faros da Costa da Morte (Galicia) (2001), Caminando entre dólmenes: arquitectura megalítica en la Costa da Morte (Galicia) (2002). Besides, he collaborated with other researchers in the following publications: 'Galician-Castilian Vocabulary' in ‘Galician-Castilian Vocabulary’ in Diccionario Enciclopédico Argos Vergara. Vocabularios Catalán, Euskera, Gallego, Portugués (1984), Galician version of Diccionario Básico Ilustrado Español-Inglés-Gallego (four volumes), Diccionario Xerais da Lingua (1993), Pequeno Diccionario Xerais da Lingua (1999), Diccionario Xerais Castelán-Galego de Usos, Frases e Sinónimos (1990), Gran Diccionario Xerais da Lingua (2000), Edigal-Galego. Primeiro método audiovisual para a aprendizaxe da lingua galega (1985), Diccionario dos Nomes Galegos (1992), O teu nome (1994) and Novo Diccionario Xerais da Lingua (2002).
He is a member of the Galician Academy, the Ethnography Section at 'Padre Sarmiento' Institute of Galician Studies, the editorial staff of the magazine 'Encrucillada', the International Association of Galician Studies, the Association of Galician Translators and the Galician Association of Onomastics.