Tithonia diversifolia is an invasive shrub found in the tropical regions. The aim of this study was to investigate the chemical composition as well as anti-inflammatory and antibacterial activities of the essential oils from leaves (EOL) and inflorescences (EOI) of T. diversifolia. The essential oils (EOs) were analysed by gas chromatography with flame ionization detector and coupled with mass spectrometry. EOL and EOI are mainly composed of α-pinene and β-pinene. Both EOL and EOI displayed potent anti-oedematogenic properties at concentrations starting at 0.5 and 2.5% (v/v), respectively. Similar to non-steroidal anti-inflammatory drugs, both EOs inhibited oedema but did not inhibit cellular recruitment. EOI displayed more potent antimicrobial activity against cariogenic microorganisms than EOL. Both EOs significantly inhibited the production of acids by Streptococcus mutans at concentrations that were nontoxic to human gingival fibroblasts (concentrations from 25 to 125 µg/mL for EOL and from 25 to 250 µg/mL for EOI).