The 18-year-old, who has made one senior appearance for Los Blancos, had six months left to run on his previous deal.
However, despite having been linked to the likes of Arsenal and Chelsea in recent weeks, the striker has now agreed to remain at the Bernabeu until 2021.
Mayoral has scored 12 goals for Madrid's second string side Castilla this season.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Liverpool | 16 | 12 | 3 | 1 | 37 | 16 | 21 | 39 |
| 2 | Chelsea | 17 | 10 | 5 | 2 | 37 | 19 | 18 | 35 |
| 3 | Arsenal | 17 | 9 | 6 | 2 | 34 | 16 | 18 | 33 |
| 4 | Nottingham ForestNott'm Forest | 17 | 9 | 4 | 4 | 23 | 19 | 4 | 31 |
| 5 | Bournemouth | 17 | 8 | 4 | 5 | 27 | 21 | 6 | 28 |
| 6 | Aston Villa | 17 | 8 | 4 | 5 | 26 | 26 | 0 | 28 |
| 7 | Manchester CityMan City | 17 | 8 | 3 | 6 | 29 | 25 | 4 | 27 |
| 8 | Newcastle UnitedNewcastle | 17 | 7 | 5 | 5 | 27 | 21 | 6 | 26 |
| 9 | Fulham | 17 | 6 | 7 | 4 | 24 | 22 | 2 | 25 |
| 10 | Brighton & Hove AlbionBrighton | 17 | 6 | 7 | 4 | 27 | 26 | 1 | 25 |
| 11 | Tottenham HotspurSpurs | 17 | 7 | 2 | 8 | 39 | 25 | 14 | 23 |
| 12 | Brentford | 17 | 7 | 2 | 8 | 32 | 32 | 0 | 23 |
| 13 | Manchester UnitedMan Utd | 17 | 6 | 4 | 7 | 21 | 22 | -1 | 22 |
| 14 | West Ham UnitedWest Ham | 17 | 5 | 5 | 7 | 22 | 30 | -8 | 20 |
| 15 | Everton | 16 | 3 | 7 | 6 | 14 | 21 | -7 | 16 |
| 16 | Crystal Palace | 17 | 3 | 7 | 7 | 18 | 26 | -8 | 16 |
| 17 | Leicester CityLeicester | 17 | 3 | 5 | 9 | 21 | 37 | -16 | 14 |
| 18 | Wolverhampton WanderersWolves | 17 | 3 | 3 | 11 | 27 | 40 | -13 | 12 |
| 19 | Ipswich TownIpswich | 17 | 2 | 6 | 9 | 16 | 32 | -16 | 12 |
| 20 | Southampton | 17 | 1 | 3 | 13 | 11 | 36 | -25 | 6 |
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