In general, the tribute visibly moved the audience in the Nokia Theatre crowd, according to The Independent.
On the other hand, one of the clips of Williams cracking jokes in stand-up and during televised interviews shown in the tribute was deemed racist by critics.
In one stand-up performance, the late comedian borrows a pink scarf from an audience member in the front row, wraps it around his head mimicking an Islamic headscarf called Hijab, and cries, "I would like to welcome you to Iran. Help me!"
Numerous viewers immediately took to Twitter to condemn the inclusion of the particular snippet in the tribute.
"After that, people who'd never heard of Robin Williams would think he's Billy Crystal's racist friend who was on a lot of talk shows?" Eric Harvey tweeted.
"I'm still so shocked that the #Emmys would include such a racist bit in Robin Williams tribute. Out of all his great work, really?" Ava also wrote.
Crystal has yet to comment on the criticisms.
A source told Hollywood Life Crystal is "prepared for this moment for his friend" and he is "humbled to have been chosen and has gone through all emotions to be ready."
In his tribute to Williams, Crystal mentioned he and the late comedian "could be funny anywhere" and they were "such close friends."
"He made us laugh. Hard. Every time you saw him, on television, movies, nightclubs, arenas, hospitals, homeless shelters for our troops overseas. And even in a dying girl's living room for her last wish, he made us laugh. Big time," Crystal said of Williams.
Meanwhile, Henry Holt and Co. has announced it had acquired a planned biography of the late actor to be written by Dave Itzkoff but the book's title and publication date are yet to be announced, according to The Garden Island.