Van Dijk spent nine months on the sidelines after suffering a serious knee injury against Everton in October last year.
The former Southampton defender missed the rest of the 2020/2021 season as well as EURO 2020 because of the injury.
Van Dijk appeared as a 68th minute substitute alongside another long-term absentee, Joe Gomez, as Liverpool lost 4-3 to their German counterparts in Austria.
Writing on Twitter after the game, Van Dijk said: “285 days ago, I started on a journey back towards playing. It’s hard to express how I am feeling, but it’s important to me that I say I feel blessed to have had the support of so many incredible people.
“The surgeon, my physios, coaches and staff who have been with me in my corner since day one. My team-mates for giving me energy and keeping my head up. The fans for their love, support and encouragement. And most of all, my family because without them, I’d be nothing. Thank you.
“The work doesn’t stop now. It’s only just starting. We keep going!”
Van Dijk will have three more games to build up his fitness before Liverpool's first Premier League game against Norwich City on August 14.
The Reds will take on Bologna, Osasuna and Athletic Bilbao in the rest of their pre-season games.
