In this paper, the flower‐shaped microstrip antenna (FSMA) is investigated theoretically and experimentally for the first time. A theoretical model is proposed to investigate the radiation characteristic of an FSMA using conformal mapping technique. The flower shape is mapped to a circular shape with the help of an appropriate mapping relation. The wave equation is solved in the transformed domain using Galerkin technique to obtain the approximate solution of eigenfunction and eigenvalue. Resonant frequency, internal field patterns, input impedance, and far‐field radiation patterns of the FSMA are investigated. Three antenna prototypes are fabricated for experimental verification. The acceptable agreement is found among the calculated, simulated, and measured data. Our theory shows an error of less than 1.45% in predicting the resonance frequency. Quality factor and bandwidth are also described. This theoretical approach not only quickly evaluates the performance of an FSMA but also provides the instruction to design an FSMA.