Lallana has had an injury-hit campaign, missing the start of the season and then not featuring since the end of March due to a hamstring injury.
But the England international came off the bench in Liverpool’s 4-0 win over Brighton in the final league game of the season.
It puts Lallana in contention for the Champions League final on May 26 and Gareth Southgate’s England squad for the World Cup.
Lallana has been a key player for Klopp but he has expressed his shock at how his players coped without him.
Klopp told Sky Sports: “What the boys did this season was unbelievable.
“We missed Adam Lallana for the whole year and I can’t believe we have achieved this without him.”
He added: ”I’m really proud of the boys, a nearly perfect season. We had no chance to challenge Man City so the only thing you can go for is a Champions League spot. It is a big thing.
“We had a few more chances today, it’s fantastic that Mo Salah could break the record and Dom and Robertson could score. It’s hard to be a young player in this fantastic side, Solanke has struggled a bit but he has shown up today. I’m really happy for him.”
Klopp then reserved some special words for Mohamed Salah who scored his 32nd league goal of the season and said he is confident Liverpool can challenge Man City.
He said: ”When everyone tells you-you are fantastic all season it is hard to stay on track so I am pleased with Mo Salah. Congratulations to Man City, it is incredible to get 100 points, Thoroughly deserved. We need more consistency to challenge and a little bit more luck with injuries.
“But we have got a lot of experience from this season. We have matured and we will do that again. In our good moments it is not easy to play better football. We will add to the squad, we need more players but I’m a big believer in developing the team. These boys made a big step.”