The Frenchman was rumoured to have picked up an ankle injury that would have kept him out for the rest of the season, but he was fit enough to start semi final at the London Stadium.
Before coming back against Eintracht Frankfurt, Zouma had missed the impressive second leg win against Lyon and was absent over the weekend too as the Hammers lost to Chelsea.
He was monumental again as he always has been since signing for the club in the summer.
There is no doubt that when the French defender is in the team, the Hammers look strong and comfortable with his experience and pedigree.
Eintracht Frankfurt have the perfect night
The night though belonged to the colourful German side, who shot ahead in the first minutes after a brilliant build-up play with Ansgar Knauff finishing off smartly.
This gave the visitors a quick lead and silenced the home fans.
The goal then kicked West Ham into life, and Jarrod Bowen should have equalised after he was played in on goal but his shot hit the post and came back into play.
They did not have to wait for long though with Kurt Zouma heading across from a free-kick, for Michail Antonio to level for claret and blue side.
The goal brought all the good things out of the Hammers, but they just could not get a second before the interval.
After the break, Eintracht Frankfurt again took the lead again after some sensational play gave Daichi Kamada a simple finish, and this time tried as the Irons did, they could not get the equaliser.
Substitute Said Benrahma and the usually-clinical Jarrod Bowen both came close to getting the goal that would have seen West Ham go to Germany with a draw, but it wasn’t to be.
Given that the Hammers went to France to beat Lyon, they will be confident that they can still reach the final in Seville.
But they will have to work for it on the evidence of the impressive Frankfurt display in London.