The Reds endured a miserable 2025/26 campaign, finishing fifth in the Premier League without a trophy. They also exited the Champions League and FA Cup in the quarter-finals and were knocked out of the League Cup in the fourth round.
Liverpool lost 19 of their 56 matches in all competitions, including 12 Premier League games.
Now, with Andoni Iraola taking charge, Van Dijk believes Liverpool have an opportunity to put last season behind them and restore their standards.
"Last year was unacceptable. This year we have an opportunity to turn that around," Van Dijk said.
"We all know how tough that will be but if you're not up for the challenge, then you're not at the right place.
"What I feel at the moment is everyone is up for the challenge. Let's see how we go about it."
Van Dijk insisted Liverpool should not need to prove their quality to outside critics, but said the squad must show greater commitment to the club.
"I don't think we have a point to prove to anyone," he said.
"We have to show how much we care, how much we want to fight for this badge and also realise how privileged we are to be playing for Liverpool."
Iraola has been brought in to bring greater intensity and energy to Liverpool's football after his successful spell with Bournemouth.
The new manager has already highlighted concerns over the squad's fitness, saying during pre-season that some players were only capable of maintaining their intensity for around 30 minutes.
Van Dijk believes keeping the squad fit will be crucial if Liverpool are to compete for trophies on multiple fronts.
"We need everyone to be fit. We need a squad which is able to compete on all four fronts and that's the only way to try to be successful," he said.
The Liverpool captain has also been encouraged by what he has seen from Iraola's team so far.
"If you look at Bournemouth last year, I think they were pretty exciting," Van Dijk said.
"I would say if we keep working, keep believing, keep showing our quality then we can be very excited."
Liverpool begin their Premier League campaign away to Newcastle United at St James' Park on Sunday, with Iraola set to take charge of the Reds in a competitive match for the first time.
