The Spain striker, 32, has signed a contract with the Club until 2019.
Fernando joined Swansea from Spanish side Sevilla in August, 2016, and scored 15 goals in 33 Premier League appearances last season.
A product of Athletic Bilbao’s academy, he scored 111 goals in 327 games at the Basque club before he joined Juventus in July, 2013, where he netted 27 times in 92 appearances.
Fernando was a key part of two Serie A and one Italian Cup winning sides at Juventus and won the 2016 Europa League with Sevilla.
He has represented Spain on 24 occasions, scoring seven goals, and was a member of the 2010 World Cup winning squad.