A system and method for accelerating a threat mitigation of malicious cybersecurity activity includes: identifying, via one or more processors, a cybersecurity event associated with a third-party application or a third-party service of a subscriber; generating, via the one or more processors, a service-proposed remediation action for the cybersecurity event based on the identifying of the cybersecurity event; automatically assessing, via the one or more processors, the service-proposed remediation action against automated remediation criteria of the subscriber based on the generation of the service-proposed remediation action; automatically constructing, via the one or more processors, a remediation action application programming interface (API) request for the service-proposed remediation action based on the service-proposed remediation action satisfying the automated remediation criteria of the subscriber; and automatically executing, via the one or more processors, the remediation action API request to remediation or mitigate a suspected cybersecurity threat associated with the cybersecurity event.