1998 Seattle Mariners season Game log September

| Date_ | Opponent | Score | Loss | Attendance | Record |
|---|---|---|---|---|---|
| September 11 | @ Kansas City Royals | 5-8 | Swift (11-9) | 18874 | 67-79 |
| September 12 | @ Kansas City Royals | 2-5 | Moyer (13-9) | 28091 | 67-80 |
| September 14 | @ Minnesota Twins | 10-3 | Radke (11-14) | 9711 | 68-80 |
| September 15 | @ Minnesota Twins | 12-7 | Rodriguez (4-6) | 8024 | 69-80 |
| September 16 | @ Oakland Athletics | 4-1 | Heredia (3-2) | 12371 | 70-80 |
| September 17 | @ Oakland Athletics | 8-0 | Candiotti (11-16) | 11707 | 71-80 |
| September 18 | @ Anaheim Angels | 5-3 | DeLucia (2-6) | 39902 | 72-80 |
| September 19 | @ Anaheim Angels | 3-5 | Spoljaric (4-5) | 42833 | 72-81 |
| September 20 | @ Anaheim Angels | 1-3 | Abbott (2-1) | 42972 | 72-82 |
| September 21 | Oakland Athletics | 5-2 | Heredia (3-3) | 30076 | 73-82 |
| September 22 | Oakland Athletics | 7-6 | Witasick (1-2) | 20908 | 74-82 |