The 'Brown Eyed Girl' singer has been announced as the final headliner for the music concert series, which will take place in July 2021.
Van's headline show will take place on Tuesday 6 July, 2021, with tickets going on sale at 10am on Friday 7 August.
The 74-year-old musician rose to fame in the mid-1960s, starring as the lead singer of R&B and rock band, Them, before he started his solo career in 1967 and released his iconic song, 'Brown Eyed Girl'.
Meanwhile, Van previously insisted he is in the most prolific songwriting period of his career and he has "momentum" as of right now.
When asked if he feels like he's on a roll, he said: "I do, definitely. I mean, it's difficult to answer these kinds of questions, because one doesn't really know. It just is what it is, and it feels like there is momentum at this time. I don't really like to question what I do ... I don't have to, you know. It's not necessary for me to question it. It's probably just momentum."
The Northern Irish singer also admits that not working under pressure makes the creative process more enjoyable.
He explained: "There is a difference when you are doing it under duress. In the old days I was doing it under duress.
"The way things were worked out, I was doing it in between gigs, and it was very pressurised. Now it's not, because I manage it and produce it myself. I'm not going through a record company. I deliver the product to the record company. In the old days it was a very different thing."
James Blunt (7 July), DJ Spoony x Garage Classical (8 July), Will Young and James Morrison (9 July), Bananarama (10 July) and Gipsy Kings (11 July) are also all scheduled to perform during the week-long extravaganza at the beautiful and iconic setting of the Royal Botanic Gardens, Kew.