1990 King Cup
The 1990 King Cup was the 32nd season of the knockout competition since its establishment in 1956. Al-Hilal were the defending champions but they were eliminated by Al-Riyadh in the Round of 16. This season was the final season of the competition. the Cup then returned under the name of King Cup of Champions in 2008.
Al-Nassr won their 6th title after defeating Al-Taawoun 2–0 in the final. By reaching the final Al-Taawoun became the second Prince [Mohammad bin Salman League|First Division] side to reach the final after Al-Riyadh in 1978. As winners of the tournament, Al-Nassr qualified for both the 1991 [Arab Cup Winners' Cup] and the 1991–92 [Asian Cup Winners' Cup].
Bracket
Note: H: Home team, A: ''Away team''Round of 16
The matches of the Round of 16 were held on 3 and 4 May 1990.| Home team | Score | Away team |
| Al-Riyadh | 3–1 | Al-Hilal |
| Al-Wehda | 1–1 | Al-Ahli |
| Al-Suqoor | 0–2 | Al-Taawoun |
| Damac | 1–1 | Al-Nahda |
| Al-Qadsiah | 2–2 | Al-Ettifaq |
| Al-Raed | 1–2 | Al-Shabab |
| Al-Nassr | 3–1 | Hajer |
| Al-Ittihad | 3–1 | Al-Tai |
Quarter-finals
The matches of the Quarter-finals were held on 10 and 11 May 1990.| Home team | Score | Away team |
| Al-Taawoun | 2–1 | Al-Shabab |
| Al-Ittihad | 1–1 | Al-Riyadh |
| Al-Wehda | 2–0 | Al-Nahda |
| Al-Nassr | 3–1 | Al-Ettifaq |