A computer-implemented method for determining the healthiness of nodes within computer clusters may include (1) identifying a computer cluster that includes a plurality of nodes configured to provide substantially continuous availability of at least one application, (2) identifying at least one operating system kernel installed on at least one of the nodes, (3) configuring the operating system kernel to (a) asynchronously monitor performance of the node and (b) determine, based at least in part on the node's performance, whether the node is sufficiently healthy to execute the application, (4) receiving a notification from the operating system kernel that indicates that the node is not sufficiently healthy to execute the application, and then (5) performing at least one action configured to enable the computer cluster to provide substantially continuous availability of the application despite the unhealthy node. Various other systems, methods, and computer-readable media are also disclosed.