The disciplinary action stemmed from a custody case involving Smith's ex-girlfriend, who in February 2017 filed a petition alleging that Smith has a "history of substance abuse and illicit drug usage" and "a history of being physically violent" toward her.
Smith, who was seeking sole custody of the couple's child, denied all the charges when they came to light in November, but he was apologetic for his actions in a statement released by the team Tuesday.
"I would like to sincerely apologize to my former girlfriend, the NFL, the Ravens organization, my coaches, my teammates, my fiancée and all our fans," said Smith in the statement. "I'm very disappointed that my past actions have led to this suspension. I promise that I have already learned much and will continue to learn more from this experience. I believe I am, and will continue to try to be, a better person and a better father because of this. I am committed to being the best I can be, both on and off the field."
It is the second four-game suspension in as many seasons for the eighth-year cornerback. Smith was suspended four games in December for violating the league's performance-enhancing drug policy -- a ban that came after he suffered a torn Achilles.
"I take full responsibility for my past conduct," said Smith. "Moving forward, I will work with the NFL and the Ravens to ensure that what happened in the past will never happen again. I will take all necessary steps to be a positive role model for both my sons, for the NFL and for the entire Ravens community."
A first-round pick of the Ravens in the 2011 NFL Draft, the 30-year-old Smith has played all 16 games in two of his seven seasons. He matched his career high with three interceptions in 2017.
Baltimore released a statement in which the team said it fully supported the NFL's decision to suspend Smith.
"The NFL found evidence of threatening and emotionally abusive behaviors by Jimmy toward his former girlfriend that showed a pattern of improper conduct," the statement read. "Our player's behavior was inappropriate and wrong. As an organization, we have carefully reviewed the matter to determine the appropriate course of action for our team to take as Jimmy's employer."