Former Valencia Coach has been appointed as the new Las Palmas boss to replace Manolo Marquez, who resigned on Tuesday.
The 54-year-old, a previous long-term assistant to Rafael Benitez, had been out of work since his dismissal from Los Che in September 2016.
Pako spent eleven seasons as assistant to Rafael Benitez at Extremadura, Tenerife, Valencia and Liverpool before branching out to become a number one elsewhere.
He has since managed at Mexican sides Tecos and Santos Lugana alongside Israeli club Maccabi Tel Aviv before a short-lived stint at the Mestalla, winning three of the 12 matches in charge.
Ayestaran arrives at Las Palmas accompanied by two assistants, David Caneda and Jose Viela. Paquito Ortiz will continue to be part of the technical staff.
Los Amarillos sit 15th in La Liga with two wins and four defeats from their six league outings, and travel to Barcelona this weekend.