Eilish then started rapping Ludacris' verse from Bieber's 2009 hit "Baby."
The 18-year-old also pulled out a ukulele and performed songs she created as a kid before launching into "Ocean Eyes" and "All The Good Girls Go to Hell" with the late night host.
"That song is the reason that I have the life I have," she said about "Ocean Eyes" which kickstarted her career at 13-years-old.
Eilish and Corden visited her home where she had recorded her album When We Fall Asleep, Where Do We Go? inside her brother Finneas' bedroom.
Cordon became uncomfortable while holding Eilish's pet spider.
Eilish is nominated for six Grammy awards including Album of the Year, Record of the Year and Best New Artist.