The 67-year-old Mexican was presented at Mestalla after taking charge following his spell as Mexico coach at the 2026 World Cup. He has signed until the end of the season, with an option linked to Europa League qualification, although sporting director Braulio Vázquez has indicated that an extension could be agreed regardless of where Valencia finish.
Aguirre has previously managed Osasuna, Atlético Madrid, Zaragoza, Espanyol, Leganés and Mallorca in Spain and has often taken charge of teams facing difficult circumstances.
He admitted that several offers had been available to him before Valencia called.
"I can't say no to Valencia. Never, never. It's a historic club in La Liga, it has a fantastic fanbase. You come here and you're blown away," Aguirre said.
"I want Mestalla to be an imposing stadium and I want the team to return to the levels it deserves and has reached throughout its history."
Aguirre said he had been spending time with his family before the offer arrived.
"I had put four offers to one side. I was with my family, with my wife, Silvia, and my grandchildren. And I said to Silvia: 'I'm sorry, but we have to go there.'"
His immediate priority is the first match against Racing Santander at El Sardinero. Aguirre rejected the idea of making long-term declarations about the season before he has properly assessed his squad.
"I don't know how to imagine things. What the little piece of paper says in the contract doesn't tell me much. If we're all comfortable, we'll continue, and if we're not comfortable, we won't continue."
The new coach has already identified injuries as an immediate concern and said he needs more time before making decisions about recruitment.
"The first thing I see is that there are a lot of injured players and that's what concerns me at the moment. We have to get them back and change that face," he said.
"I don't have a diagnosis of how the team is yet. I'm an employee of the club, I don't control the budget or the money."
Aguirre also praised the young players he has inherited and suggested age will not determine his selections.
"I saw the emergence of Otorbi and Mayol. I don't look at age. If the player is good enough, go ahead," he said.
"I arrived at Espanyol and it was full of youngsters, but I turned to four veterans and we saved the team. There are 31 matches left. The players who are in the best condition will play."
He believes the squad has enough ability but needs confidence.
"I see a lot of individual talent, a lot of academy players and a lot of quality. The only thing we have to do is convince them that they are important, that they are at an institution that is important," Aguirre said.
"You can't wander around the pitch at a club with the history of Valencia. You have to give them confidence and make them believe in themselves. The quick diagnosis is that we lack confidence."
Aguirre was equally direct about what he wants from his players.
"I don't understand football if there isn't commitment. If you see a passive player, you have to make him react. I was a fairly clumsy footballer, but nobody could beat me for giving everything. Commitment is non-negotiable."
And he has little interest in promising supporters anything beyond the next fixture.
"People are tired of messages. Enough with messages. We're going to play against Racing. We're going to try to win as soon as possible. That's the best message."