Kim Kardashian , Justin Bieber and Suni Lee all hit an event on Tuesday ... but no, it wasn't for an awards show -- it was all thanks to IShowSpeed !!

The streaming superstar hosted a night at the Los Angeles Memorial Coliseum ... and a bunch of A-listers were present for the premiere of his six-episode YouTube series, "Speed Goes Pro."

Some of the biggest celebrities rolled through in support ... including Kim K, who chatted with Speed about his 35-day tour that wrapped up in L.A. She also brought some of her kids to meet him ... earning her some major cool mom points. Play video content

JB also pulled up rockin' furry shades and a hoodie ... and jammed out to DJ TJ Mizell 's tunes -- even when his own track, "Speed Demon," came on.

Speed was shocked to see Olympic

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