The Barca star was given the all clear after taking part in a training session at Camp Nou, and he should take his place in the team for the Champions League encounter.
The Spain international has been back in training since Friday, but assistant coach Jordi Roura had previously declined to confirm whether he would be available. The 33-year-old took part in the Catalan side's last training session on Tuesday leading up to the match, and he should take his place in the starting XI as the Catalans look to overturn the two-goal deficit from the first leg.
"Xavi Hernandez has been passed fit to play in tonight’s big game against Milan after this lunchtime’s training session on the Camp Nou pitch," a statement on the official club website read. "Xavi had already been named in the 19-man matchday squad, but was finally given the medical all clear to play this lunchtime."
Goals from Kevin-Prince Boateng and Sulley Muntari gave the Italian side a 2-0 win at the San Siro in the first leg, meaning Barcelona has its work cut out if it is to advance to the quarterfinals of the competition.