World population and their nutrient requirement increase day by day. Farmers try to obtain much more crop per area and for this reason they use abundant artificial fertilizer, and also spend a lot of money for fertilization. But these fertilizers create a serious pollution in the nature. So, nowadays the scientist study to develop a new formula biofertilizer or biostimulant that consists organic substances. For this aim they use microorganisms. Cyanobacteria has a highly diversity group that consists of photosynthetic prokaryotic microorganisms. Cyanobacteria that produce lots of metabolites such as amino acids, proteins, vitamins etc. have a wide spread. In this study, the effects of different concentrations of Spirulina platensis (Gomont) Geitler extracts on the germination of Capsicum annuum L.seeds and root-stem length, lateral root number and wet-dry weight were investigated. The application of S5 (100% cell extract) showed an inhibitory effect on seed germination. S2 (25% cell extract) and S3 (50% cell extract) applications had a positive effect on germination and seedling development in pepper. As a result; cyanobacterial extract has positive effects on seed germination and plant growth-development and it is possible to produce a commercial and ecological biostimulant by developing different extract concentrations.