I don't have anything for this season, but Barcelona had a possession percentage of 63.5 in the Champions League in 2025-26.
StatMuse has Champions League data for possession going back to the 2015-16 season.
More Barcelona Stats
2026-27 Table
| CLUB | M | W | D | L | GD | PTS | |
|---|---|---|---|---|---|---|---|
10 | 2 | 0 | 1 | 1 | -1 | 1 | |
11 | 0 | 0 | 0 | 0 | 0 | 0 | |
12 |  Barcelona | 0 | 0 | 0 | 0 | 0 | 0 |
13 | 0 | 0 | 0 | 0 | 0 | 0 | |
14 | 0 | 0 | 0 | 0 | 0 | 0 |
Rayo
Real Madrid
Valencia
Osasuna