Most home runs in a Major League Baseball season by a second baseman
- Who
- Marcus Semien
- What
- 45 total number
- Where
- Not Applicable
- When
- 2021
The most home runs in a season by a second baseman is 45 by Marcus Semien (USA) while playing for the Toronto Blue Jays (Canada) in 2021. Semien surpassed the previous mark of 43 by Davey Johnson of the Atlanta Braves in 1973.