In early 2019, Kudaibergen participated in the CBS talent competition The World's Best, in which he was presented to the US audience as the "Six Octave Man" and "man with the world's widest vocal range". He performed "SOS d'un terrien en détresse" in the audition round and "All by Myself" in the battle round. Despite being listed as front-runner, Kudaibergen withdrew from the competition after his performance of "Adagio" in the champions round (semi-final), citing that he wished to leave the opportunity to younger performers (the other two contestants of this round were the 13-year-old Indian pianist Lydian Nadhaswaram and the 12-year-old Kazakh singer Daneliya Tuleshova).
On 13 June 2019, he released his first album, iD, in China. It reached platinum status within 37 seconds after release, and triple-platinum within the first hour.
He held his second large-scale solo concert, Arnau, in the Astana Arena in Nur-Sultan, Kazakhstan, on 29 June 2019, and the sell-out performance attracted 40.000 people from 64 countries.
In 2019, the collaboration with Igor Krutoy continued with the songs "Mademoiselle Hyde", "Love is Like a Dream" (Russian: Любовь, похожая на сон), "Know" (Russian: Знай), "Olimpico" (also known as "Ogni Pietra"), "Where Love Lives" (Russian: Там, где живет любовь), "Passione", "Ulisse" (duet with Aida Garifullina) and "Ti Amo Così" (with Aida Garifullina and Lara Fabian), "Love of Tired Swans" (Russian: Любовь уставших лебедей) . In October and November, he joined Krutoy as a guest performer on the Igor Krutoy Anniversary Tour, performing in New York City, Dubai, Minsk, and Düsseldorf.
On 5 December 2019, Kudaibergen was awarded "Best Vocalist in Classical Music" and won a Special Prize for "Discovery of the Year" at the Russian National Music Awards "Victoria" that are considered the Russian equivalent to the Grammy Awards.
Kudaibergen gave his first solo concert in the USA on 10 December 2019. The show was titled Arnau Envoy and took place at the Barclays Center in New York. The venue was sold out with 19,000 spectators from 63 countries.
Among Kudaibergen's 2019 performances in Russia were his guest performances at the New Wave in Sochi, his headlining performance at the closing ceremony of the WorldSkills championships in Kazan, and the Igor Krutoy Anniversary Gala on Ice in Moscow.