Background: Tagetes erecta L. has been traditionally used for treatment of skin diseases. Objectives: This study aimed to evaluate in vitro skin anti-aging, antioxidant, antibacterial activities, and human skin irritation of T. erecta flower extract for development as a cosmeceutical skin product using aqueous, 50%, and 95% ethanolic extracts of T. erecta flower. Methods: Total phenolic content was defined. Quantitative analysis of syringic acid was determined by using HPLC. Antioxidant activities were performed by measurement of 2,2-diphenyl 1-pichylhydazyl free radical scavenger. Anti-aging assays were monitored inhibitory effects on tyrosinase, elastase, hyaluronidase, and collagenase activities. Antibacterial effects against Staphylococcus aureus and Staphylococcus epidermidis was also investigated. The extract was formulated as a lotion and its stability study was evaluated and human skin irritation tests were performed. Results: The 95% ethanolic extract had significantly higher total phenolic content and syringic acid content than the other extracts. The 95% ethanolic extract also had stronger inhibitory activities on DPPH scavenging and against tyrosinase, elastase and hyaluronidase enzyme activities than those of 50% ethanolic or water extracts. The 95% ethanolic extracts showed a better antibacterial activity against S. aureus and S. epidermidis. The developed lotion containing 1% of T. erecta extract using 95% ethanol was stable. Moreover, skin irritation was not observed in healthy volunteers after applying the T. erecta lotion. Conclusion: This study indicates that T. erecta flower extracts, especially a 95% ethanolic extract, are potential sources for development of cosmeceutical skin products against enzymes/reactions responsible for skin aging and bacterial skin infection.