Childish Gambino's "This is America" is a blatant ripoff of a track that sounds similar, has a similar name and was all over the Internet almost 2 years before the rapper's smash hit was released ... so claims a musician in a new lawsuit.

Emelike Nwosuocha, a rapper who performs under the name Kidd Wes, is suing Childish Gambino, AKA Donald Glover, claiming he ripped off his song, "Made in America."

According to Kidd Wes ... he created his track on SoundCloud in September 2016 and released it on YouTube a couple months later, where people could listen to it for free. He says he also registered the song with the U.S Copyright Office in May 2017, and it was set to be the lead single on his upcoming album.

As you likely know ... Gambino's "This is America" was released in 2018, became incredibly popular and went on to win Grammy for Record of the Year.

According to the docs ... Kidd Wes claims the chorus, or hook, of "This is America" is "unmistakably substantially similar, if not practically identical" to his "Made in America."

READ ALL ABOUT IT AT TMZ