November 13, 1989: Jeff Schaefer was signed as a free agent by the Mariners.[3]
December 7, 1989: Pete O'Brien was signed as free agent by the Mariners.[4]
Regular season
June 2: Randy Johnson threw a no-hitter versus the Detroit Tigers,[5][6] the first for the franchise.[7] He was also the tallest pitcher (6 ft 10 in (2.08 m)) in Major League history to throw a no-hitter. It was the 2101st game in Mariners history, played on a Saturday night in the Kingdome.
September 14: Ken Griffey Sr. and Ken Griffey Jr. hit back-to-back home runs in the top of the first inning against the California Angels.[8] Through 2022, it remains the only occurrence of consecutive homers by a father and son in MLB history.
Ken Griffey, Sr. joined his son (Ken Griffey Jr.) to become the first father and son to play in a game together. The game was played in the Kingdome against the Kansas City Royals on August 31.[15] The Griffeys became the first father-and-son teammates to hit back-to-back home runs on September 14.[8]
Line Score
August 31, Kingdome, Seattle, Washington
Team
1
2
3
4
5
6
7
8
9
R
H
E
Kansas City
0
2
0
0
0
0
0
0
0
2
6
2
Seattle
3
0
0
0
1
0
1
0
x
5
10
1
W: Johnson (13-8) L: Davis (7-10)
Home Runs: Pecota (4) Attendance: 27,166 Time: 2:27
Batting
Kansas City Royals
AB
R
H
RBI
Seattle Mariners
AB
R
H
RBI
Seitzer, 3b
4
0
0
0
Reynolds, 2b
5
0
1
0
McRae, cf
4
0
1
0
Griffey, lf
4
1
1
0
Tartabull, dh
3
0
1
0
Griffey Jr., cf
4
1
1
0
Jackson, lf
3
1
1
0
Davis, dh
2
3
2
1
Macfarlane, c
4
0
1
0
O'Brien, 1b
3
0
0
0
Eisenreich, rf
3
0
0
1
Buhner, rf
3
0
2
1
Pecota, 1b
3
1
1
1
Martinez, 3b
2
0
1
1
White, 2b
3
0
1
0
Schaefer. 3b
2
0
1
1
Jeltz, ss
3
0
0
0
Bradley, c
4
0
1
0
NONE
0
0
0
0
Vizquel, ss
3
0
0
0
Totals
30
2
6
2
Totals
32
5
10
4
Pitching
Kansas City Royals
IP
H
R
ER
BB
SO
Davis L (7-10)
6.2
9
5
4
6
1
Sanchez
1.1
1
0
0
0
0
Totals
8.0
10
5
4
6
1
Seattle Mariners
IP
H
R
ER
BB
SO
Johnson W (13-8)
7.1
5
2
2
2
4
Swift SV (3)
1.2
1
0
0
0
0
Totals
9.0
6
2
2
2
4
Player stats
= Indicates team leader
Batting
Starters by position
Note: Pos = Position; G = Games played; AB = At bats; H = Hits; Avg. = Batting average; HR = Home runs; RBI = Runs batted in
^"Griffeys make history". Lawrence Journal-World. (Kansas). Associated Press. September 1, 1990. p. 1B.
^Johnson, Lloyd, and Wolff, Miles, ed., The Encyclopedia of Minor League Baseball, 2nd and 3rd editions. Durham, North Carolina: Baseball America, 1997 and 2007