This study aims to identify and characterize a novel extrasolar planetary system. To achieve this, periodic transit events were analyzed within the light curves obtained from the Transiting Exoplanet Survey Satellite (TESS). To determine the nature of the transiting object, its mass was estimated using radial velocity measurements. TOI 1147 was subsequently observed utilizing the STELLA Échelle Spectrograph (SES) at the Izaña Observatory, Tenerife. The light curves of TOI 1147 exhibit a periodic dimming event occurring every 10.9 days. Over approximately 280 days of observational data, the same periodicity detected in TESS data was confirmed. These measurements made it possible to determine the system architecture and parameters. The newly discovered exoplanet, TOI 1147 b, has a derived mass of 1.3 𝑀𝐽 and a radius of 2.3 𝑅𝐽, classifying it as a "puffy" exoplanet. Moreover, its orbit is highly elliptical, with an eccentricity of 𝑒 = 0.64. Spectroscopic analysis using SES provided insights into the host star, particularly through the evaluation of the H𝛼-Index. The results indicate that TOI 1147 is a Sun-like, low-activity star undergoing stellar evolution. Additionally, radial velocity data revealed the presence of a third, long-period companion in the system, which was not detected via transit observations. This object also exhibits a high eccentricity. These findings contribute to the broader understanding of planetary system diver- sity and formation mechanisms.