Year 1999 (MCMXCIX) was a common year of the Gregorian calendar that started on a Friday. It is the first year of SpongeBob SquarePants, and the year of Season 1 episodes.
Template:Timeline/year| Date | Event(s) | |
|---|---|---|
| May 1 | "Help Wanted," "Reef Blower," and "Tea at the Treedome," the pilot episodes, premiered. The show premiered. | |
| July 17 | Bubblestand and Ripped Pants premiered. The show officially began. | |
| July 31 | Jellyfishing and Plankton! premiered. | |
| August 7 | Naughty Nautical Neighbors and Boating School premiered. | |
| August 14 | Pizza Delivery and Home Sweet Pineapple premiered. | |
| August 21 | Mermaid Man and Barnacle Boy and Pickles premiered. | |
| August 28 | Hall Monitor and Jellyfish Jam premiered. | |
| August 31 | SpongeBob SquarePants gets picked up for a 2nd season. | |
| September 4 | Sandy's Rocket and Squeaky Boots premiered. | |
| September 11 | Nature Pants and Opposite Day premiered. | |
| September 18 | Culture Shock and F.U.N. premiered. Nicktoons Racing was released. | |
| September 25 | MuscleBob BuffPants and Squidward the Unfriendly Ghost premiered. | |
| October 2 | The Chaperone and Employee of the Month premiered. | |
| October 28 | Scaredy Pants and I Was a Teenage Gary premiered. | |
| December 31 | SB-129 and Karate Choppers premiered. | |