An unlockable character is a hidden character that must be unlocked by completing certain criteria before being able to play as them. Every game in the Mario Kart series besides Super Mario Kart, Mario Kart 64 and Mario Kart: Super Circuit have unlockable characters.
Mario Kart: Double Dash!! has a total of 4 unlockable characters,
Mario Kart DS has a total of 4 unlockable characters.
- Daisy - Receive a gold trophy in 50cc Lightning Cup.
- Waluigi - Receive a gold trophy in 100cc Lightning cup.
- Dry Bones - Receive a gold trophy in 50cc Special cup.
- R.O.B. - Receive a gold trophy in Mirror Special Cup.
Mario Kart Wii has a total of 14 unlockable characters.
- Baby Daisy - Earn a star in every single 50cc Wii cup.
- Baby Luigi - Unlock eight expert staff ghosts in Time Trials.
- Birdo - Play 16 Time Trials or win 250 Wi-Fi races.
- Bowser Jr. - Earn a star in every single 100cc Retro cup.
- Daisy - Win the 150cc Special Cup.
- Diddy Kong - Complete 50cc Lightning Cup
- Dry Bones - Win the 100cc Leaf Cup.
- Dry Bowser - Earn a star in every single 150cc Wii cup.
- Funky Kong - Unlock four expert staff ghosts in Time Trials.
- King Boo - Win the 50cc Star Cup.
- Mii (Outfit A) - Win the 100cc Special Cup.
- Mii (Outfit B) - Unlock all expert staff ghosts in Time Trials.
- Rosalina - Have a Super Mario Galaxy save file, and win 50 races. Alternatively, earn a star in all eight Mirror Mode cups.
- Toadette - Play Time Trials on all thirty two courses or win 1000 Wi-Fi races.
Mario Kart 7 has a total of 9 unlockable characters.
- Daisy - Win the 150cc Mushroom Cup.
- Wario - Win the 150cc Flower Cup.
- Rosalina - Win the 150cc Star Cup.
- Metal Mario - Win the 150cc Special Cup.
- Shy Guy - Win the 150cc Shell Cup.
- Queen Bee - Win the 150cc Banana Cup.
- Wiggler - Win the 150cc Leaf Cup.
- Lakitu - Win the 150cc Lightning Cup.
- Mii - Win Special Cup and Lightning Cup in any engine class.
Mario Kart 8 has a total of 14 unlockable characters. Some have no concrete unlock conditions, and are unlocked after winning a random cup. However, the same cup will not unlock more than 1 character.
- Rosalina - Random
- Metal Mario - Random
- Lakitu - Random
- Toadette - Random
- Baby Rosalina - Random
- Pink Gold Peach - Random
- Iggy Koopa - Random
- Roy Koopa - Random
- Lemmy Koopa - Random
- Larry Koopa - Random
- Wendy O. Koopa - Random
- Ludwig von Koopa - Random
- Morton Koopa Jr. - Random
- Mii - Win every cup in any engine class.