The experienced and esteemed Spaniard was Rafa Benitez's assistant when Liverpool won that famous 2005 Champions League Final in Instanbul.
Clotet, who worked with Herrera at Espanyol, described him as a "massive addition of value into our Club."
Francisco 'Paco' Herrera Lorenzo retired as a player aged 32 - Sporting Gijon was among the midfielder's clubs - and moved into coaching, gaining a wealth of knowledge and enjoying some significant success.
Born in Barcelona, Herrera coached a variety of second tier clubs in Spain before joining Benitez.
On his return to his homeland after two years on Merseyside, where he also acted in a chief analyst and scouting role as well, he became director of football at Espanyol.
Under his guidance, Espanyol reached the 2007 UEFA Cup Final, losing on penalties in Glasgow to Sevilla.
After moving to Celta Vigo as head coach, he took them to the the second division Play-Off Semi-Finals and then promotion to La Liga in 2012.
At Las Palmas he repeated the promotion feat in 2015.
Herrera, 65, has most recently coached at Sporting Gijon, Aris Thessaloniki in Greece before parting company with Las Palmas during a second spell in March.
Clotet commented: "Paco has a wealth of experience. Not only as a head coach and manager at many teams in Spain, at the highest level and second league, but as a technical director too.
"At Espanyol, where he held that position, he built the team that had a fantastic season and ended up in the UEFA Cup Final.
"And he was Rafa Benitez's assistant at Liverpool when they got a lot of success and won the Champions League.
"He knows the game, he is very good on the tactical side as well. I enjoy talking football with him and he will have a lot of excellent ideas on how to help our team and our Club, going forward.
"At the same time, I also see in him a lot of motivation to help the players grow and he has a very good pedigree of helping to develop the younger ones.
"I think he is a massive addition of value into our Club."
Clotet added: "For me, the fact that he wanted to come showed how much faith he has in the Club and what we want to try and do.
"I am very honoured that he wants to work for us."
The existing coach team and backroom staff remain in place and Herrera has been added to bring further expertise.