An increase in the demand for cold-pressed vegetable oils can be observed, e.g. from sunflower. The press cake formed during sunflower oil production can also be an important source of protein, carbohydrates, and phenolic compounds. The aim of the study was to examine the quality of gluten-free breads fortified with sunflower seed cake. The fortified products were characterized by lower moisture content (49.35–48.87%). The bake loss parameter decreased after the use of the highest 15% dose of the sunflower cake. The addition of the sunflower cake caused an increase in the content of nutrients, compared to the control sample: protein (7.44–9.69%d.b.), fat (3.41–10.72%d.b.), crude fiber (1.23–2.34%d.b.), polyphenols (89.3–222.3 mg·100 gd.b.−1), and soluble sugars (2.42–2.73%d.b.). The gluten-free breads with the sunflower seed cake exhibited lower hardness, springiness, and chewiness but higher cohesiveness. The use of the additive contributed to the darkening of the gluten-free bread crumb. The appearance, consistency, aroma, and palatability of the sunflower cake-fortified gluten-free bread were found to be much more attractive than the parameters of the unmodified bread. The conducted research has shown that, thanks to sunflower cake addition, it is possible to obtain a highly nutritious product with desirable sensory quality.