Zabaleta began his football career in his native Argentina, for San Lorenzo de Almagro. The defensive midfielder came through San Lorenzo's youth ranks, debuting as a 16 year old in 2002. The young Zabaleta had already been involved in representative football for Argentina, having played for Argentina U15s as a 14 year-old, and was on his way to play for his country 75 times at age group level. Zabaleta spent three seasons at San Lorenzo, making 79 appearances with 8 goals.
2005 saw Pablo move to Spanish side Espanyol for €3 million, after captaining Argentina U20s to victory in the 2005 Youth World Cup. The highlight of his time in Spain was helping the side to the UEFA Cup Final in 2007, where they lost to fellow Spaniards Sevilla on penalties. 2005 also saw his debut for the senior national side, in a 1-0 loss to Paraguay. He has represented Argentina 14 times.
The summer of 2008 was a big moment for Zabaleta. He travelled to Beijing, China for the 2008 Olympics, where he played every game at right-back for Argentina as they won the Gold Medal. Following the tournament, he was purchased by Mark Hughes at Manchester City for an undisclosed sum, being assigned the number 5 shirt.
Since joining Zabaleta has been a valuable squad member, and starting midfielder and defender. He played his 100th game for City on New Years Day 2011, and was a substitute in the Blue's FA Cup win in 2011.