The purpose of this research was analyse the influence of the phenolic and flavonoid components and antioxidant activity of functional flavoured yoghurt supplemented with guava extracts (GE) (seeds, green and red leaves and juice) to assess these effects as antioxidant and antibacterial. The findings indicated that all guava extracts exhibit antioxidant activity employing (DPPH, ABTS) techniques with enhanced activity during cold storage and antibacterial activity against tested microorganisms. Addition of guava extracts to yoghurt notably (pulp, leaves) enhanced sensory characteristics, increased total solids and protein content, didn't influence the acidity and pH. All yoghurt samples were protected against development of spoilage and harmful bacteria and enhanced growth and viability of lactic acid bacteria (LAB) (LAB). GE-fortified yoghurt's total phenolic compounds (TPC), as well as individual phenolics content and antioxidant activity, rose progressively and dramatically during the course of cold storage, according to the findings. TPC has a significant impact on the antioxidant activity of GE-fortified yoghurts. According to the findings, GE may be utilised to make functional dairy products that are higher in nutritional content and have more biological activity.