A typical 1 cup sliced serving of fennel contains 1.1 grams of protein (1.24 g per 100 g), which makes it only a minor source of protein. That covers roughly 2% of the 50 g reference Daily Value, so it adds toward your protein total for the day.
Around 16% of the calories in fennel come from protein, so it is more of an energy food than a protein food. It contributes to a day's protein total, but the bulk of what it delivers is energy rather than amino acids - treat it as a contributor alongside a denser source, not as the protein in a meal.
Among the 105 vegetables in the database, fennel ranks 77th by protein per serving, and 722nd out of all 796 foods on the site. Set against rutabaga, another vegetable entry in the database, a serving carries about 0.5 g less protein (rutabaga has 1.6 g per 1 cup cubes cooked).
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 87 g. The per-100 g figure lets you compare it directly against any other food here, whatever its serving.
Source: USDA FoodData Central #169385 - "Fennel, bulb, raw" (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
Fennel protein FAQ
How much protein is in fennel per 100 g?
Fennel has 1.24 g of protein per 100 g. A typical 1 cup sliced serving (87 g) provides 1.1 g.
Is fennel a complete protein?
No. Fennel 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 fennel cover?
A 1 cup sliced serving of fennel contains 1.1 g of protein, about 2% of the 50 g reference Daily Value.
Is fennel a good source of protein?
Fennel is only a minor source of protein, and about 16% of its calories come from protein, which makes it more of an energy food than a protein food. Set against rutabaga, another vegetable entry in the database, a serving carries about 0.5 g less protein (rutabaga has 1.6 g per 1 cup cubes cooked).