The 27-year-old was officially presented as a Bilbao player on Friday after completing a £800,000 move from Alaves.
"There were several teams interested in me. I had people tell me about Athletic and the wonderful environment," Inside Spanish Football quotes the forward as saying.
"They told me this was a family and that I couldn't let this chance pass me by.
"It's true that others wanted me, but when Athletic contacted me, I didn't have to think twice. This club, their history, just who they are, there was no doubt."
Viguera started his youth career with Real Sociedad.