- Mohamed Salah (5')
- Diogo Jota (8')
- Luis Díaz (59')
- Mathias Honsak (10')
Diogo Jota and Mohamed Salah had Jurgen Klopp's team up 2-0 inside of 10 minutes before Mathias Honsak answered for Darmstadt, who earned promotion back to the top flight in Germany last season after a six-year absence.
The hosts dominated proceedings and added their third just before the hour-mark with a cheeky flick from Luis Diaz at the near post that redirected Liverpool newcomer Dominik Szoboszlai's corner kick into the back of the net.
Liverpool, who finished fifth in the Premier League last campaign and will play in the Europa League this season, face Chelsea at Stamford Bridge on Sunday as 2023-24 action begins in England's top flight.
The match took place at Deepdale as Liverpool continues an expansion project on the Anfield Road stand, which is expected to be completed by October.