Various embodiments of the present invention are directed to a convertible children's high chair. According to various embodiments, the convertible high chair generally comprises a first child seat supported above a floor by a high chair frame, and a second child seat configured for being removably coupled to first child seat. The second child seat is configured such that, when detached from the high chair's first child seat, it can be used apart from the high chair as a booster seat (e.g., secured to the seating surface of a standard chair or another support surface). In certain embodiments, the second child seat includes a base surface configured to stably support the second child seat on a separate support surface (e.g., without the need to be attached to or mounted on a separate base or support member).