| Competition: | S. League |
| Season: | 1998 |
| Winners: | Singapore Armed Forces 2nd S.League title |
| Continentalcup1: | Asian Club Championship |
| Continentalcup1 Qualifiers: | Singapore Armed Forces |
| Matches: | 110 |
| Total Goals: | 368 |
| League Topscorer: | Stuart Young (22) |
| Biggest Home Win: | Home United 9-3 Gombak United (18 July 1998) |
| Biggest Away Win: | Gombak United 1-6 Home United (20 May 1998) |
| Highest Scoring: | Home United 9-3 Gombak United (18 July 1998) |
| Prevseason: | 1997 |
| Nextseason: | 1999 |
The 1998 S.League was the third season of the S.League, the top professional football league in Singapore. Teams played each other once both home and away, in a 20-match season.
The 1998 S.League was won by Singapore Armed Forces, their second consecutive title.
Jurong left Bukit Gombak Stadium upon completion of their new home ground Jurong East Stadium. Home United also relocated, leaving Jalan Besar Stadium to move into Bishan Stadium. Two new teams entered into the competition – Gombak United (who took the place of Jurong playing at Bukit Gombak Stadium) and Marine Castle United who made Hougang Stadium their home – taking the number of participating teams to eleven. Tiong Bahru United were renamed Tanjong Pagar United for the 1998 season.
| Team | Stadium | Capacity | Location | |
|---|---|---|---|---|
| Toa Payoh Stadium | 3,900 | Toa Payoh | ||
| Bukit Gombak Stadium | 3,000 | Bukit Batok | ||
| Bedok Stadium | 3,900 | Bedok | ||
| Jurong East Stadium | 2,700 | Jurong East | ||
| Bishan Stadium | 4,000 | Bishan | ||
| Hougang Stadium | 3,000 | Hougang | ||
| Jurong Stadium | 6,000 | Jurong | ||
| Yishun Stadium | 3,400 | Yishun | ||
| Tampines Stadium | 3,600 | Tampines | ||
| Queenstown Stadium | 3,800 | Queenstown | ||
| Woodlands Stadium | 4,300 | Woodlands |
Each club is allowed to have up to a maximum of 5 foreign players.
| Club | Player 1 | Player 2 | Player 3 | Player 4 | Player 5 | |
|---|---|---|---|---|---|---|
| None | ||||||
| None | None | None | None | |||
| None | None | None | None | |||
| None | None | None | ||||
| None | None | |||||
| None | None | |||||
| None | ||||||
| None | None | None | None | None |
Singapore Armed Forces qualified to compete in the 1999–2000 Asian Club Championship. This was their second appearance in continental competition. The club met with more success than in their first appearance, defeating Royal Dolphins of the Cambodian League 11–3 on aggregate in the East Asian first round. They were defeated in the second round by Sinthana of the Thai Premier League, going down 3–2 on aggregate.
| Rank | width='150' | Name! | width='140' | Club! | Goals |
|---|---|---|---|---|---|
| 1 | Stuart Young | Home United | 22 | ||
| 2 |  Bogdan Brasoveanu | Tampines Rovers | 20 | ||
| 3 |  Goran Paulić | Balestier Central | 19 | ||
| 4 |  Egmar Goncalves | Home United | 16 | ||