diff --git a/config/config_test.go b/config/config_test.go
index 6c5e3662a3151..42aefff151761 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -12,6 +12,7 @@ import (
 	"github.com/influxdata/telegraf/plugins/inputs/http_listener_v2"
 	"github.com/influxdata/telegraf/plugins/inputs/memcached"
 	"github.com/influxdata/telegraf/plugins/inputs/procstat"
+	"github.com/influxdata/telegraf/plugins/outputs/azure_monitor"
 	httpOut "github.com/influxdata/telegraf/plugins/outputs/http"
 	"github.com/influxdata/telegraf/plugins/parsers"
 	"github.com/stretchr/testify/assert"
@@ -257,3 +258,23 @@ func TestConfig_BadOrdering(t *testing.T) {
 	require.Error(t, err, "bad ordering")
 	assert.Equal(t, "Error loading config file ./testdata/non_slice_slice.toml: Error parsing http array, line 4: cannot unmarshal TOML array into string (need slice)", err.Error())
 }
+
+func TestConfig_AzureMonitorNamespacePrefix(t *testing.T) {
+	// #8256 Cannot use empty string as the namespace prefix
+	c := NewConfig()
+	defaultPrefixConfig := `[[outputs.azure_monitor]]`
+	err := c.LoadConfigData([]byte(defaultPrefixConfig))
+	assert.NoError(t, err)
+	azureMonitor, ok := c.Outputs[0].Output.(*azure_monitor.AzureMonitor)
+	assert.Equal(t, "Telegraf/", azureMonitor.NamespacePrefix)
+	assert.Equal(t, true, ok)
+
+	c = NewConfig()
+	customPrefixConfig := `[[outputs.azure_monitor]]
+	namespace_prefix = ""`
+	err = c.LoadConfigData([]byte(customPrefixConfig))
+	assert.NoError(t, err)
+	azureMonitor, ok = c.Outputs[0].Output.(*azure_monitor.AzureMonitor)
+	assert.Equal(t, "", azureMonitor.NamespacePrefix)
+	assert.Equal(t, true, ok)
+}
diff --git a/plugins/outputs/azure_monitor/azure_monitor.go b/plugins/outputs/azure_monitor/azure_monitor.go
index f2b1db1dd6868..a90dac049d6eb 100644
--- a/plugins/outputs/azure_monitor/azure_monitor.go
+++ b/plugins/outputs/azure_monitor/azure_monitor.go
@@ -155,10 +155,6 @@ func (a *AzureMonitor) Connect() error {
 		Timeout: a.Timeout.Duration,
 	}
 
-	if a.NamespacePrefix == "" {
-		a.NamespacePrefix = defaultNamespacePrefix
-	}
-
 	var err error
 	var region string
 	var resourceID string
@@ -646,7 +642,8 @@ func (a *AzureMonitor) Reset() {
 func init() {
 	outputs.Add("azure_monitor", func() telegraf.Output {
 		return &AzureMonitor{
-			timeFunc: time.Now,
+			timeFunc:        time.Now,
+			NamespacePrefix: defaultNamespacePrefix,
 		}
 	})
 }