diff --git a/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp b/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
index b8032fcec8..8ad2f7521e 100644
--- a/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
+++ b/esphome/components/mcp23xxx_base/mcp23xxx_base.cpp
@@ -4,6 +4,8 @@
 
 namespace esphome::mcp23xxx_base {
 
+void IRAM_ATTR mcp23xxx_gpio_intr(Component *arg) { arg->enable_loop_soon_any_context(); }
+
 template<uint8_t N> void MCP23XXXGPIOPin<N>::setup() {
   this->pin_mode(flags_);
   // When interrupt_pin is configured, pin_mode() already auto-enables CHANGE
diff --git a/esphome/components/mcp23xxx_base/mcp23xxx_base.h b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
index 1c45b0f4af..7414677175 100644
--- a/esphome/components/mcp23xxx_base/mcp23xxx_base.h
+++ b/esphome/components/mcp23xxx_base/mcp23xxx_base.h
@@ -8,6 +8,10 @@ namespace esphome::mcp23xxx_base {
 
 enum MCP23XXXInterruptMode : uint8_t { MCP23XXX_NO_INTERRUPT = 0, MCP23XXX_CHANGE, MCP23XXX_RISING, MCP23XXX_FALLING };
 
+// Not a template member: GCC 10 (ESP8266) ignores section attributes on template instantiations, leaving the
+// ISR in flash.
+void IRAM_ATTR mcp23xxx_gpio_intr(Component *arg);
+
 template<uint8_t N> class MCP23XXXBase : public Component, public gpio_expander::CachedGpioExpander<uint8_t, N> {
  public:
   virtual void pin_mode(uint8_t pin, gpio::Flags flags);
@@ -35,7 +39,8 @@ template<uint8_t N> class MCP23XXXBase : public Component, public gpio_expander:
   void setup_interrupt_pin_() {
     if (this->interrupt_pin_ != nullptr) {
       this->interrupt_pin_->setup();
-      this->interrupt_pin_->attach_interrupt(&MCP23XXXBase::gpio_intr, this, gpio::INTERRUPT_FALLING_EDGE);
+      this->interrupt_pin_->attach_interrupt(&mcp23xxx_gpio_intr, static_cast<Component *>(this),
+                                             gpio::INTERRUPT_FALLING_EDGE);
       this->set_invalidate_on_read_(false);
     }
     // Disable loop until an input pin is configured via pin_mode()
@@ -43,7 +48,6 @@ template<uint8_t N> class MCP23XXXBase : public Component, public gpio_expander:
     // For polling mode, loop is re-enabled when pin_mode() registers an input pin
     this->disable_loop();
   }
-  static void IRAM_ATTR gpio_intr(MCP23XXXBase *arg) { arg->enable_loop_soon_any_context(); }
 
   // read a given register
   virtual bool read_reg(uint8_t reg, uint8_t *value) = 0;