The Annex is mainly residential, with tree-lined one-way streets lined with Victorian and Edwardian homes and mansions, most of them built between 1880 and the early 1900s.

The Annex is densely populated. The stretch of Bloor Street between St. George and Bathurst is a vibrant social and mixed use area, offering to Toronto a wide range of services from upscale dining to discount retailers like Honest Ed's, in buildings which often include residential space in upper floors. Between Bathurst and Christie, street signs on that stretch of Bloor call it the Koreatown. During the 1950s and 1960s, an influx of Hungarian immigrants moved into the neighbourhood after the 1956 Hungarian Revolution was suppressed, and many of the businesses and properties along Bloor are owned by Hungarian-Canadian families.

The Annex real estate shows many examples of a uniquely Toronto style of house that was popular among the city's elite in the late nineteenth century. Examples of these Annex homes can be found in both The Annex and within the University of Toronto campus. The style of Annex homes is thus known as the "Annex style" house.

Annex style homes typically feature large rounded Romanesque arches along with Queen Anne style decorative items such as turrets. Attics are emphasized in the exterior architecture. The houses are most often made of brick, though some also incorporate Credit Valley Sandstone. Built for many of the city's wealthiest citizens the houses are also large.

The Annex Statitsics