Edible flowers have been gaining popularity among researchers, nutritionists and chefs all around the world. Nowadays, flowers are used to make food look and/or taste better; however, they are also a very good source of valuable nutrients (antioxidants, vitamins, proteins, fats, carbohydrates, macro and microelements). The aim of our study was to determine the content of dietary fibre and total protein in selected edible flowers; we also compared the nutritional content of petals, differentiating between the representatives of the Oleaceae and Asteraceae families, as well as herbaceous vs. woody plants. The study material consisted of petals of 12 edible flower species (Magnolia × soulangeana, Sambucus nigra L., Syringa vulgaris L. (white and violet flowers), Robinia pseudoacacia, Forsythia × intermedia, Cichorium intybus L., Bellis perennis, Tussilago farfara L., Taraxacum officinale F.H. Wiggers coll., Centaurea cyanus L., Calendula officinalis). Dietary fibre content was determined by the enzymatic-gravimetric method and ranged from 13.22 (Magnolia × soulangeana) to 62.33 (Calendula officinalis L.) g/100 g. For insoluble dietary fibre (IDF), the values ranged from 8.69 (Magnolia × soulangeana) to 57.54 (Calendula officinalis L.) g/100 g, and the content of soluble dietary fibre (SDF) was between 1.35 (Syringa vulgaris L.-white flowers) and 7.46 (Centaurea cyanus L) g/100 g. Flowers were also shown to be a good, though underappreciated, source of plant protein, with content ranging from 8.70 (Calendula officinalis L.) to 21.61 (Magnolia × soulangeana) g/100 g dry matter (Kjeldahl method). Considerable amounts of protein were found in the flowers of the olive family (Oleaceae) and woody plants, which can enrich the daily diet, especially vegan and vegetarian. Edible flowers of the Asteraceae family, especially the herbaceous representatives, contained high levels of both total dietary fibre and its insoluble fraction; therefore, they can be a rich source of these nutrients in the daily diet of athletes, which would perform a prebiotic function for gut bacteria.