应用防火墙（英语：Application firewall），一种防火墙，经由应用程序或服务来控制网络封包的流入、流出与系统调用，因为运作在OSI模型中的应用层而得名。它能够监控网络封包，阻挡不符合防火墙设置规则的封包进入、离开以及调用系统调用（system calls）。这类防火墙，通常又可以分成以网络为基础的应用防火墙（network-based application firewalls）与以主机为基础的应用防火墙（host-based application firewalls）二者。

An application firewall is a form of firewall that controls input, output, and/or access from, to, or by an application or service. It operates by monitoring and potentially blocking the input, output, or system service calls that do not meet the configured policy of the firewall. The application firewall is typically built to control all network traffic on any OSI layer up to the application layer. It is able to control applications or services specifically, unlike a stateful network firewall, which is - without additional software - unable to control network traffic regarding a specific application. There are two primary categories of application firewalls, network-based application firewalls and host-based application firewalls.