Yelich was born in Thousand Oaks, California, and attended Westlake High School. During his freshman year, he batted . 373 with 25 hits and 16 strikeouts in 67 at bats. In his sophomore year, he batted . 341 with 31 hits and 24 strikeouts in 91 at bats. During Yelich's junior year, he batted . 489 with 46 hits and struck out 6 times. In his senior year, he batted . 451 with 37 hits, nine strikeouts and nine home runs in 82 at bats. He was named Second Team All-American by Max Preps and was ranked 34 among the top 100 players in the nation in high school.