The experienced keeper has finalised a loan deal from AC Milan for the rest of the season after completing a medical.
The former Liverpool stopper returns to the Premier League following a six-year absence after Villa’s number one Tom Heaton was ruled out for the remainder of the campaign.
England international Heaton sustained a knee injury in Villa’s 2-1 victory at Burnley on New Year’s Day.
Reina, 37, watched Villa’s 6-1 home defeat against Manchester City on Saturday from the stands. The Spaniard will battle it out with Orjan Nyland for a starting place between the posts with head coach Dean Smith having to decide who is going to play against Brighton this weekend.
And Reina is confident he will quickly fit in at Villa Park and is ready for the challenge ahead.
He said: “It is a great dressing room, and I have been told they are great lads.
“Now we need a mentality to be strong and to be ready for a good battle.
“We need to play with discipline and remain determined. These kinds of things need to be our basics.”
Smith added: “We’ve managed to secure a player in Pepe who has a wealth of Premier League experience.
“At the start of the summer we were looking for an experienced goalkeeper and brought in Tom Heaton.
“Unfortunately, his injury has ruled him out for the rest of the season but Pepe fits our criteria not just because of his experience, but also because of his leadership qualities.”
Reina spent nearly a decade at Anfield before moving to Bayern Munich in 2014. He then joined Napoli after just one season in Germany. A move to AC Milan followed but Reina has featured just once this term.