[1] Undrafted out of high school, Mejias-Brean attended the University of Arizona, where he played college baseball for the Wildcats.

[5] He split the 2013 season between the Dayton Dragons and the Bakersfield Blaze, hitting .305/.379/.457/.836 with 11 home runs and 82 RBI.

[7][8] He split the season between Louisville, the Double–A Arkansas Travelers, and the Triple–A Tacoma Rainiers, combining to hit .268/.328/.346 with four home runs and 50 RBI.

[10] He spent the 2019 minor league season with the El Paso Chihuahuas, hitting .316/.367/.455/.822 with 11 home runs and 66 RBI.

[15] Mejias-Brean split the year between the Double-A Bowie Baysox and the Triple-A Norfolk Tides, slashing .234/.321/.390 across 64 games.

[19] On January 26, 2023, Mejias-Brean was named the hitting coach for the Single-A Modesto Nuts, with Vincej as the manager, for the 2023 season.