The Reds overturned their 3-0 first leg deficit to qualify for the final 4-3 aggregate.
A pair of goals from Divock Origi and Georginio Wijnaldum achieved the magic for the Premier League side.
Keita was not involved in the match after he suffered a thigh injury during the first leg at Camp Nou.
The injury ended his season and places his chances of playing for Guinea in the 2019 Africa Cup of Nations at risk.
The midfielder has taken to social media to applaud his teammates for their incredible comeback against Barcelona.
“So proud of my boys,” Keita posted on Instagram.
The 24-year-old also posted a video on Instagram where he removed his recovery pad while celebrating the win in his living room.
And here’s Naby Keita celebrating last night’s win on Snapchat! 📹— Steven Gerrard (@Gerrard8FanPage) May 8, 2019
That laugh at the end! 🤣❤️ pic.twitter.com/mWWdZ1LODu