A typical 1 cup cubes baked serving of acorn squash contains 2.3 grams of protein (1.12 g per 100 g), which makes it only a minor source of protein. That covers roughly 5% of the 50 g reference Daily Value, so it adds toward your protein total for the day.
Only about 8% of the calories in acorn squash come from protein, so it is more of an energy food than a protein food. It is worth eating for other reasons; the protein it adds to a day is incidental.
Among the 105 vegetables in the database, acorn squash ranks 41st by protein per serving, and 633rd out of all 796 foods on the site. Set against oyster mushrooms, another vegetable entry in the database, a serving carries about 0.5 g less protein (oyster mushrooms has 2.8 g per 1 cup sliced).
It is an incomplete protein on its own; pairing it with other plant foods across the day covers the full range of essential amino acids. The serving above is measured by volume at 205 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #169293 - "Squash, winter, acorn, cooked, baked, without salt" (SR Legacy, published 4/1/2019). Values are the published reference figures for that record, not lab measurements for a specific brand or batch.
Quick answers
Acorn squash protein FAQ
How much protein is in acorn squash per 100 g?
Acorn squash has 1.12 g of protein per 100 g. A typical 1 cup cubes baked serving (205 g) provides 2.3 g.
Is acorn squash a complete protein?
No. Acorn squash is an incomplete protein on its own; pairing it with other protein sources across the day covers the full range of essential amino acids.
How much of the Daily Value does a serving of acorn squash cover?
A 1 cup cubes baked serving of acorn squash contains 2.3 g of protein, about 5% of the 50 g reference Daily Value.
Is acorn squash a good source of protein?
Acorn squash is only a minor source of protein, and about 8% of its calories come from protein, which makes it more of an energy food than a protein food. Set against oyster mushrooms, another vegetable entry in the database, a serving carries about 0.5 g less protein (oyster mushrooms has 2.8 g per 1 cup sliced).