Mark McCall's side beat Leinster in last season's showpiece in Newcastle, but the Premiership champions will have to overcome stiff opposition if they are to reach next season's final in Marseille, France.
The defending champions are joined in Pool Four by two-time European Cup winners Munster, French juggernauts Racing 92 and Ospreys.
Saracens and Munster, who have met in the knockout stages of the competition in three of the last four seasons, will renew their rivalry just six months after they met in the last four in April.
Last year's beaten finalists Leinster head up Pool One alongside Lyon, Benetton Rugby and Northampton Saints, who lost to the Irish province in the 2013 final of the competition.
Premiership runners-up Exeter Chiefs will be hopeful of making the quarter-finals for the first time since 2016 after being handed a favourable draw.
Rob Baxter's side will play last season's Champions Cup quarter-finalists Glasgow Warriors, Premiership rivals Sale Sharks and Challenge Cup runners-up La Rochelle in Pool Two.
Harlequins have been rewarded for their top-six finish in the Premiership with a place in Pool Three alongside Clermont, Ulster and Bath.
Beaten Premiership semi-finalists Gloucester will be hoping to build on their impressive domestic campaign last year by making strides forward in Europe.
The Cherry and Whites will face-off against Top 14 champions Toulouse, Montpellier and Connacht in Pool Five.
The pool stages will kick off later this year to make way for the World Cup in Japan.
The first round of games is scheduled for the weekend of 15/16/17 November.
Draw in full
Champions Cup dates
Round 1: 15/16/17 November, 2019
Round 2: 22/23/24 November, 2019
Round 3: 6/7/8 December, 2019
Round 4: 13/14/15 December, 2019
Round 5: 10/11/12 January, 2020
Round 6: 17/18/19 January, 2020
Quarter-finals: 3/4/5 April, 2020
Semi-finals: 1/2/3 May, 2020
Final: 23 May, 2020.
BT Sport is the only you can watch every single minute of the 2019/20 Champions Cup. If you're not already a customer, click here to find out how you can get set up ahead of the new season.