Pique fell heavily in the early stages of Barcelona's 1-1 draw with Atletico Madrid in Tuesday's UEFA Champions League quarter-final first leg and was subbed off soon after.
Barca initially described the injury as pelvic bruising but further tests after the match showed Pique suffered a 'crack' in his right hip, although the club's description of the damage ensured there is still doubt over the exact nature of the problem.
"Pique will be out for four weeks for an acetabular tear in his right hip," a statement on Barcelona's website read.
An acetabular labral tear is damage to the cartilage and tissue in the hip socket.
In the eighth minute of Tuesday's match, Pique and Atleti striker Diego Costa contested a high ball and the former fell awkwardly, before being replaced by Marc Bartra four minutes later.
The injury is expected to keep Pique on the sidelines for both next week's second leg of the continental quarter-final in Madrid and the Copa del Rey final versus Real Madrid on April 16 in Valencia.
The 27-year-old defender's absence will also severely dent Barcelona's hopes of winning La Liga and could see the Catalan club miss out on silverware this season.
Pique has played 36 matches in all competitions for Barca this season, starting all of them.
