The former Spain international left his position at San Lorenzo in Argentina to take over at a club who are without silverware since 2008.
And Pizzi revealed he is delighted to have made the switch to Mestalla.
"I'm very happy and excited to have the chance to take Valencia to the place that it has always belonged," he is quoted as saying by Marca.
"It's one of the biggest teams in Spain and Europe, and I think that it has the potential to grow and return to the place that it has always belonged."
Valencia currently sit 11th in La Liga, 26 points adrift of leaders Barcelona, and Pizzi has asked for "a lot of hard work and calmness" as he takes on his new role.
The Argentina-born coach also has a UEFA Europa League knockout campaign to look forward to, with Valencia set to face Dynamo Kiev in the last 32.
The new manager, who replaces the sacked Miroslav Djukic, will be joined at Valencia by physio Alejandro Richino and assistant Manuel Suarez.
