The men's competition begins on 13 and 14 September, with champions SC Magdeburg beginning their title retention attempt at home to Telekom Veszprém.
Elsewhere, returning side Montpellier HB face a tough start by welcoming Barça to the Sud de France Arena, plus new boys Kolstad Handball make the journey from Norway to Bitola, North Macedonia to face HC Eurofarm Pelister, who themselves are making a first appearance in the EHF Champions League since the 2005/06 season.
Before that, the EHF Champions League Women begins on 9 and 10 September.
In the first round in women's competition, we will see a repeat of last season's quarter-final, as FTC-Rail Cargo Hungaria host Metz. Reigning champions Vipers Kristiansand travel to Denmark to take on Ikast Håndbold.
DVSC Schaeffler of Hungary, making their first appearance in the women's competition since 2010/11, will start their journey at home against IK Sävehof.
Excitingly, fans need only to wait until the second round of fixtures to see the first repeat of last season's final; Vipers Kristiansand will welcome FTC-Rail Cargo Hungaria to Norway on 16 or 17 September.
The final round of men's fixtures is scheduled for 6 March 2024, while the women's groups are due to be completed on 17 February 2024.
Click the links for the full schedules for both the EHF Champions League Women and the Machineseeker EHF Champions League.