The final was played between Real Madrid and Liverpool at the NSC Olimpiyskiy in Kyiv, Ukraine.

[7] 79 teams from 54 of the 55 UEFA member associations participated (the exception being Liechtenstein, which did not organise a domestic league).

[13][14] Apart from the allocation based on the country coefficients, associations could have additional teams participating in the Champions League, as noted below: In the default access list, the Champions League title holders entered the group stage.

[12] However, since Real Madrid already qualified for the group stage (as the champions of the 2016–17 La Liga), the Champions League title holders berth in the group stage was given to the Europa League title holders, Manchester United.

[19][20] The schedule of the competition was as follows (all draws were held at the UEFA headquarters in Nyon, Switzerland, unless stated otherwise).

The losing teams in both sections entered the 2017–18 UEFA Europa League play-off round.

The losing teams in both sections entered the 2017–18 UEFA Europa League group stage.

The draw for the group stage was held on 24 August 2017, 18:00 CEST, at the Grimaldi Forum in Monaco.

Qarabağ were the first team from Azerbaijan to play in the Champions League group stage.

In the knockout phase, teams played against each other over two legs on a home-and-away basis, except for the one-match final.

[40] The award winners were announced and presented during the 2018–19 UEFA Champions League group stage draw in Monaco on 30 August 2018.