Hernandez, an attacking midfielder, has been an important member of the Costa Rica national football team at various levels, playing in the U-20 World Youth Championship in Argentina. He also represented the country in the U-23 team at the 2004 Summer Olympics.
Hernandez has played in 30 international matches for his country, including in the 2010 World Cup qualifiers. He last played for Costa Rica in February 2010. Since 2009, he has been playing for Australian A-League side Melbourne Victory.
He was the top scorer last season in A-League with 10 goals, totalling 36 goals in 122 games in five seasons of A-League. He was the recipient of Johnny Warren Award for best player in the A-League for 2009-10. He is reputed for his ability to score from middle and long distances.
Prayag United Sports Club finished seventh in the I-League last season.
Apart from roping in Hernandez, the club was also building its defence and attack with inclusion of top notch players like Subrata Paul, Gouramangi Singh and Ranti Martins.
Hernandez said, "I am really happy to be associated with Prayag United Sports Club. I am looking forward to this new opportunity and challenges. It has indeed been a big decision to move to India, but I feel that there is this huge zest and enthusiasm for football here. I am excited to be part of this excellent team and hope to contribute to the success of the team in the coming season."