The use of synthetic drugs for the treatment of cancer is often accompanied by toxic side effects. Thus, the alternative use of readily available and inexpensive medicinal plants is the panacea to the toxic side effects associated with synthetic drugs. This study aimed to phytochemical screening of different constitutive secondary metabolites classes of two Khaya species, i.e., K. senegalensis and grandifoliola from the Meliaceae plants. In addition, a precise and fast LC-MS/MS screening was performed to identify the constituents of the second species together with the evaluation of their potential in vitro antioxidant and antitumor activities. It is worth mentioning that the phytochemical and biological examinations were carried out on the 70% methanol extracts of the aerial parts and their MeOH-soluble portions (MSP). The preliminary phytochemical screening tests, two-dimensional paper chromatography (2D-PC), thin layer chromatography (TLC) and LC-MS/MS analysis were applied for the phytochemical evaluation.LC-MS/MS analysis, on MSP of K.grandifoliola, led to the identification of 33 flavonoids, including 10 different flavonoidal aglycones (1–10) and 23 glycosides (11–33), most of which are of O-type and based on kaempferol and quercetin, 2 chalcones (30,31) and 1 anthocyanin (33). In addition, 11 phenolic acid derivatives (34–44) and 1 stilbene glycoside (92) were identified as polyphenolics-type metabolites alongside three coumarins (45–47). Among other major natural products types that were identified are 13 organic acid derivatives (48–60) 17 purine and pyrimidine derivatives (61–77), 6 amino acid derivatives (78–83), and 8 sugars and polyhydric alcohol derivatives (84–91). The identification process depends on the matching of R_t-values, molecular and fragment/s monoisotopic masses and fragmentation pathways with the open literature and library databases. Antioxidant activity was determined using several protocolsand antitumor activity evaluated against Ehrlich ascites carcinoma cells (EACC). Findings of all antioxidant assays for investigated extracts revealed significant activity with respect to the reference antioxidant agentsthat can be attributed to their high polyphenolic contents,particularly flavonoids and phenolic acids.The aqueous 70% methanol extracts of the two Khaya species recorded higher activity than the corresponding MSP. At the same time, K.senegalensissamples are more effective than the corresponding ones of K. grandifoliola and generally, the order of the activity was 70% extract_{(senegalensis)}> MSP_{(senegalensis)}> 70% extract_{(grandifoliola)} > MSP_{(grandifoliola)}. The promising antioxidant and antitumor findings of all extractsrevealed good broad-spectrum activities due to the relatively low concentrations used in comparison to the standard drugs. Therefore, the attention was directed to current extensive research for the isolation and identification the major bioactive polyphenols and deeply study their antioxidant and anticancer potentials. Results provide scientific evidence that validates the use of K. senegalensis in pharmaceutical and nutrition industries.