Scarlets will take on defending champions Bordeaux and last season's runners-up Northampton Saints in the 2025-26 Champions Cup.
Dwayne Peel's men were placed into Pool 4 for next season's edition of the European showpiece, with both sides who featured in last season's final in Cardiff set to take on the Welsh region next term.
The Parc y Scarlets outfit also come up against Bristol Bears, Bulls and Pau.
As for the Challenge Cup, Ospreys are joined in Pool 1 by fellow United Rugby Championship sides Zebre and Connacht.
Georgian side Black Lion will also lock horns with Mark Jones' men, along with French duo Montpellier and US Montauban.
Top 14 sides Lyon - who lost to Bath in last season's final at the Principality Stadium - and Perpignan are in Pool 2 with Dragons - who are also joined by Premiership Rugby outfit Newcastle Falcons and URC pair Benetton and Lions.
As for Matt Sherratt's Cardiff, they have been drawn to face URC opponents Cheetahs and Ulster along with 2019-20 Champions Cup winners Exeter.
French pair Stade Francais and Racing 92 complete the Pool 3 lineup.
Group stage fixtures commence on the weekend of 5-7 December, with the round of 16 and quarter-final matches all taking place in April 2026.
The semi-finals will be held on the opening weekend of May, with both European finals taking place at the San Mamés Stadium in Bilbao.
The Challenge Cup final will be held on Friday, May 22, with the Champions Cup final taking place a day later.
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Champions Cup draw:
Pool 1
Stade Toulousain, ASM Clermont Auvergne, Hollywoodbets Sharks, Saracens, Glasgow Warriors, Sale Sharks
Pool 2
Bath Rugby, RC Toulon, Munster Rugby, Castres Olympique, Edinburgh Rugby, Gloucester Rugby
Pool 3
Leinster Rugby, Leicester Tigers, Harlequins, Stade Rochelais, Aviron Bayonnais, DHL Stormers
Pool 4
Union Bordeaux Bègles, Scarlets, Bristol Bears, Section Paloise, Northampton Saints, Vodacom Bulls
Challenge Cup draw:
Pool 1
Ospreys, Zebre Parma, Montpellier Hérault Rugby, US Montauban, Black Lion, Connacht Rugby
Pool 2
LOU Rugby, Newcastle Falcons, Dragons, Benetton Rugby, Lions, USAP
Pool 3
Toyota Cheetahs, Cardiff Rugby, Exeter Chiefs, Racing 92, Stade Français Paris, Ulster Rugby
