Usually yes — with one question that changes the answer entirely, and most buyers never ask it.
Was it permitted?
A properly permitted, professionally finished basement is genuine value: usable space, done to code, inspected. An unpermitted development is a different proposition — it can complicate insurance, some lenders take a view on it, it must be disclosed when you sell, and if anything ever goes wrong you own the consequences entirely.
Ask for permits. If none exist, that is not automatically fatal, but it should be reflected in the price rather than paid for as though it were finished space.
Below-grade space is not valued the same as above-grade space, and buyers who assume otherwise overpay. A 2,000 square foot home with a 900 square foot developed basement is not a 2,900 square foot home, and it should not be priced as one. Appraisers treat below-grade space separately, and so does the market.
What a good basement genuinely delivers is function — a family room, a spare bedroom, an office, somewhere for teenagers. In a city where winter keeps everyone indoors for months, that function is worth real money. It is simply not worth the same per square foot as the main floor.
These get conflated constantly and are not the same thing. A developed basement is finished living space belonging to the house. A legal secondary suite is a separate dwelling with its own requirements — egress, ceiling height, separation, and registration — and it can generate income.
A legal suite is worth substantially more than a developed basement, and an illegal one is worth considerably less than either, because it carries risk the buyer inherits. If a listing says "suite", establish which kind before you value it. The Calgary secondary suite guide →
"Illegal suite" is not a small technicality in the listing copy. It affects insurance, financing, what you can legally rent it for, and what you must tell the next buyer.