The centre-back will initially join the club on a short-term deal at the start of the January transfer window, with Barca holding the option to buy the defender for €25 million (£22.6m/$28.7m) at the end of the campaign.
Murillo has endured something of a nomadic career thus far, with Barcelona set to become his eighth club, either permanent or short-term.
He spent the 2017-18 season on loan at Valencia from Inter before the Spanish club made the move permanent, but he has played just once thus far this season.
Murillo will now help to plug a hole in Barca's defence, with French centre-back Samuel Umtiti and Belgian stopper Thomas Vermaelen both struggling with injuries.
Vermaelen will be out for around a month , while Umtiti's return date is currently unkown.
Ahead of Barcelona's clash with Levante, Valverde said: "Umtiti could recover and that would be great news for us and would mean that we would have four centre-backs for the rest of the season, although three are left-footed.
"We will know more about what happens with him in a little while, but we are Barcelona and want to have a team who can respond. As I said, we'll see what happens but I'm happy to manage with what I have."
The Chelsea defender, Andreas Christensen, has been routinely mooted as a potential signing for Barca, with talks reportedly already underway between the two clubs.
However, it appears any move will now have to wait until the summer.