The 2021 Tohoku Rakuten Golden Eagles season was the 17th season of the Tohoku Rakuten Golden Eagles franchise. The Eagles played their home games at Rakuten Seimei Park Miyagi in the city of Sendai as members of Nippon Professional Baseball's Pacific League. The team was led by Kazuhisa Ishii in his first season as team manager.
Rakuten finished the season with a record of , securing third place in the PL and qualifying for the Climax Series. They were eliminated by the Chiba Lotte Marines in the First Stage in two games.
Regular season
Standings
Record vs. opponents
Interleague
Opening Day roster
Friday, March 26, 2021, vs. Hokkaido Nippon-Ham Fighters
Game log
|-align="center" bgcolor="bbffbb" | 1 || March 26 || Fighters || 8–2 || Wakui (1–0) || Uwasawa (0–1) || — || Rakuten Seimei Park || 14,559 || 1–0–0 || W1 |-align="center" bgcolor="ffbbbb" | 2 || March 27 || Fighters || 4–9 || Kato (1–0) || Takata (0–1) || — || Rakuten Seimei Park || 14,681 || 1–1–0 || L1 |-align="center" bgcolor="bbffbb" | 3 || March 28 || Fighters || 5–0 || Hayakawa (1–0) || Ikeda (0–1) || — || Rakuten Seimei Park || 14,425 || 2–1–0 || W1 |-align="center" bgcolor="bbffbb" | 4 || March 30 || @ Marines || 5–0 || Kishi (1–0) || Ojima (0–1) || — || Zozo Marine Stadium || 9,931 || 3–1–0 || W2 |-align="center" bgcolor="bbffbb" | 5 || March 31 || @ Marines || 2–1 || Norimoto (1–0) || Iwashita (0–1) || Matsui (1) || Zozo Marine Stadium || 9,594 || 4–1–0 || W3 |-