A system and method for inserting secondary content, e.g., advertisement content, graphics, images, etc., in a 360-degree immersive video environment. When a request is received from a client device for playing a video asset, a plurality of video tiles of the video asset are selected to be assembled as a video frame for delivery to the client device. A portion of the video tiles are identified that can be replaced with a corresponding set of advertisement content tiles, e.g., based on gaze vector information and/or a tile metadata specification containing advertisement insertion availability timing information with respect to each of the tiles of the video frame. After replacing the portion of the identified video tiles, the corresponding set of advertisement content tiles and remaining video tiles are assembled into the video frame including the advertisement content tiles at select locations, which is transmitted to the client device.