The 2023–24 UEFA Champions League qualifying phase and play-off round began on 27 June and ended on 30 August 2023.
The team that scored more goals on aggregate over the two legs advanced to the next round.
[4] In the preliminary round, the semi-finals and final were played as a single match hosted by one of the participating teams.
As the identity of the winners of the previous round were not known at the time of the draws, the seeding was carried out under the assumption that the team with the higher coefficient of an undecided tie advanced to the subsequent round, which meant if the team with the lower coefficient was to advance, it would simply take the seeding of its opponent.
Prior to the draws, UEFA could form "groups" in accordance with the principles set by the Club Competitions Committee purely for the convenience of the draw and not to resemble any real groupings in the sense of the competition.
Teams from associations with political conflicts as decided by UEFA could not be drawn into the same tie.
After the draws, the order of legs of a tie could be reversed by UEFA due to scheduling or venue conflicts.
[6][7][8] All matches were played on Tuesdays and Wednesdays apart from the preliminary round final.
The losers of the semi-finals and final transferred to the Europa Conference League second qualifying round Champions Path.
[3] For the winner of the preliminary round, whose identity was not known at the time of draw, the club coefficient of the highest-ranked remaining team was used.
The winners of the ties advanced to the Champions Path second qualifying round.
13 of the 15 losers were transferred to the Europa Conference League Champions Path second qualifying round and 2 losers received a bye and were transferred to the Europa Conference League Champions Path third qualifying round.
They were divided into two paths: Seeding of teams was based on their 2023 UEFA club coefficients.
[3] For the winners of first qualifying round, whose identity was not known at the time of draw, the club coefficient of the highest-ranked remaining team in each tie was used.
The winners of the ties advanced to the third qualifying round of their respective path.
They were divided into two paths: Seeding of teams was based on their 2023 UEFA club coefficients.
[3] For the winners of the second qualifying round, whose identity was not known at the time of draw, the club coefficient of the highest-ranked remaining team in each tie was used.
Prior to the draw, UEFA formed groups of seeded and unseeded teams in accordance with the principles set by the Club Competitions Committee.
The winners of the ties advanced to the play-off round of their respective path.
They were divided into two paths: Seeding of teams was based on their 2023 UEFA club coefficients.
[3] For the winners of the third qualifying round, whose identity was not known at the time of draw, the club coefficient of the highest-ranked remaining team in each tie was used.