The knockout phase involves the 16 teams which qualified as winners and runners-up of each of the eight groups in the group stage. Each tie in the knockout phase, apart from the final, is played over two legs, with each team playing one leg at home. The team that scores more goals on aggregate over the two legs advance to the next round. If the aggregate score is level, the away goals rule is applied, i.e. the team that scored more goals away from home over the two legs advances. If away goals are also equal, then thirty minutes of extra time is played. The away goals rule is again applied after extra time, i.e. if there are goals scored during extra time and the aggregate score is still level, the visiting team advances by virtue of more away goals scored. If no goals are scored during extra time, the tie is decided by penalty shoot-out. In the final, which is played as a single match, if scores are level at the end of normal time, extra time is played, followed by penalty shoot-out if scores remain tied. The mechanism of the draws for each round is as follows:
In the draw for the round of 16, the eight group winners are seeded, and the eight group runners-up are unseeded. The seeded teams are drawn against the unseeded teams, with the seeded teams hosting the second leg. Teams from the same group or the same association cannot be drawn against each other.
In the draws for the quarter-finals onwards, there are no seedings, and teams from the same group or the same association can be drawn against each other.
Qualified teams
Bracket
Round of 16
The draw was held on 12 December 2016. The first legs were played on 14, 15, 21 and 22 February, and the second legs were played on 7, 8, 14 and 15 March 2017.
Summary
Matches
6–6 on aggregate. Monaco won on away goals. ---- Real Madrid won 6–2 on aggregate. ---- Borussia Dortmund won 4–1 on aggregate. ---- Bayern Munich won 10–2 on aggregate. ---- Juventus won 3–0 on aggregate. ---- Atlético Madrid won 4–2 on aggregate. ---- Barcelona won 6–5 on aggregate. ---- Leicester City won 3–2 on aggregate.
Quarter-finals
The draw was held on 17 March 2017. The first legs were played on 11 and 12 April, and the second legs were played on 18 and 19April 2017.
Summary
Matches
Atlético Madrid won 2–1 on aggregate. ---- Monaco won 6–3 on aggregate. ---- Real Madrid won 6–3 on aggregate. ---- Juventus won 3–0 on aggregate.
Semi-finals
The draw was held on 21 April 2017. The first legs were played on 2 and 3 May, and the second legs were played on 9 and 10 May 2017.
Summary
Matches
Real Madrid won 4–2 on aggregate. ---- Juventus won 4–1 on aggregate.
Final
The final was played on 3 June 2017 at Millennium Stadium in Cardiff, Wales. The "home" team was determined by an additional draw held after the semi-final draw.
