Spain's LaLiga will be represented by at least five teams in the Champions League next season after Italy's Lazio were eliminated from the Europa League on Thursday, while Athletic Club progressed to the semi-finals.
LaLiga earned the second of two European Performance Spots handed out by UEFA, which go to associations "with the best collective performance by their clubs" in UEFA competitions.
England's Premier League was the first to secure an extra berth in Europe's top competition, on top of the four granted to the top four teams in the domestic table.
Villarreal are fifth in the LaLiga standings, with 51 points from 30 matches.
They are three points ahead of sixth-placed Real Betis and eight in front of Celta Vigo and Mallorca, with all three clubs having played one more game than Villarreal.