Celine Dion -- I Am Back and Still the Best, Bishes! (VIDEO)

Celine Dion is back on the Strip -- after a year-long hiatus she returned to her Las Vegas residency at Caesars Palace.

The Colosseum was sold-out for CD's first show since last summer ... when she stepped aside to take care of her ailing husband, Rene Angelil, who's been recovering from cancer.

The 47-year-old still nailed the high notes while running through hits like "Because You Loved Me" and "My Heart Will Go On."

Celine's scheduled to do 40 shows between now and January ... for di world!