Brenda Song was in a relationship with musician Trace Cyrus. The couple was engaged in 2011, but the engagement was later called off in 2012, and the relationship ended in 2017.

Brenda Song began dating actor Macaulay Culkin in 2017. The couple has maintained a relatively private relationship.

Brenda Song and Macaulay Culkin welcomed their first child, a son named Dakota Song Culkin, on April 5, 2021. They named him after Culkin's late sister, Dakota.

Brenda Song and Macaulay Culkin became engaged. The engagement was confirmed by various media outlets in January 2022.

Brenda Song and Macaulay Culkin welcomed their second son, Carson, around March 2023.