Messi, 30, became only the second player after Cristiano Ronaldo to reach the historic feat when his virtuoso performance in the 3-0 victory over Chelsea on Wednesday secured his 99th and 100th strike in the competition.
The Blaugrana's all-time record goalscorer also registered an assist for Ousmane Dembele's first goal for the club - in what was a complete performance to oust the Blues and advance to the quarter-finals of the Champions League.
"I'm happy to have reached 100 goals in such a beautiful competition, but the important thing was to move forward in a difficult match against a team with lots of really good players," he said after the game, as quoted by Marca.
"We managed to score early and this was important. I'm happy with how it all happened."
Messi's brace took his overall tally to 34 goals in 42 appearances across all competitions this season.