A vibration dampening system for a work vehicle may include a chassis frame extending lengthwise between a front end and a rear end. The chassis frame may include a first sidewall extending lengthwise along a first side of the frame between the front and rear ends and a second sidewall extending lengthwise along a second side of the frame between the front and rear ends. The system may also include a cab frame supported relative to the chassis frame via a suspension assembly, and a vibration damper coupled between the opposed first and second sides of the chassis frame. The vibration damper may extend lengthwise between a first end coupled to the first sidewall and a second end coupled to the second sidewall. The vibration damper is configured to reduce an amount of vibrations being transmitted through the chassis frame to the cab frame via the suspension assembly.