diff --git a/charts/kube-prometheus-stack/Chart.yaml b/charts/kube-prometheus-stack/Chart.yaml
index 467930817052..8ea20ea36c8a 100644
--- a/charts/kube-prometheus-stack/Chart.yaml
+++ b/charts/kube-prometheus-stack/Chart.yaml
@@ -21,7 +21,7 @@ name: kube-prometheus-stack
 sources:
   - https://github.com/prometheus-community/helm-charts
   - https://github.com/prometheus-operator/kube-prometheus
-version: 51.9.4
+version: 51.10.0
 appVersion: v0.68.0
 kubeVersion: ">=1.19.0-0"
 home: https://github.com/prometheus-operator/kube-prometheus
diff --git a/charts/kube-prometheus-stack/ci/03-non-defaults-values.yaml b/charts/kube-prometheus-stack/ci/03-non-defaults-values.yaml
index 541355ccdbcc..b1dfd1d599a2 100644
--- a/charts/kube-prometheus-stack/ci/03-non-defaults-values.yaml
+++ b/charts/kube-prometheus-stack/ci/03-non-defaults-values.yaml
@@ -6,3 +6,17 @@ defaultRules:
   additionalRuleGroupLabels:
     kubernetesSystem:
       key2: value2
+
+alertmanager:
+  alertmanagerSpec:
+    additionalConfig:
+      logFormat: json
+    additionalConfigString: |-
+      logLevel: {{ print "debug" | quote }}
+
+prometheus:
+  prometheusSpec:
+    additionalConfig:
+      logFormat: json
+    additionalConfigString: |-
+      logLevel: {{ print "debug" | quote }}
diff --git a/charts/kube-prometheus-stack/templates/alertmanager/alertmanager.yaml b/charts/kube-prometheus-stack/templates/alertmanager/alertmanager.yaml
index 7c2a298b3f75..52b49fc726e6 100644
--- a/charts/kube-prometheus-stack/templates/alertmanager/alertmanager.yaml
+++ b/charts/kube-prometheus-stack/templates/alertmanager/alertmanager.yaml
@@ -179,4 +179,10 @@ spec:
 {{- if .Values.alertmanager.alertmanagerSpec.minReadySeconds }}
   minReadySeconds: {{ .Values.alertmanager.alertmanagerSpec.minReadySeconds }}
 {{- end }}
+{{- with .Values.alertmanager.alertmanagerSpec.additionalConfig }}
+  {{- tpl (toYaml .) $ | nindent 2 }}
+{{- end }}
+{{- with .Values.alertmanager.alertmanagerSpec.additionalConfigString }}
+  {{- tpl . $ | nindent 2 }}
+{{- end }}
 {{- end }}
diff --git a/charts/kube-prometheus-stack/templates/prometheus/prometheus.yaml b/charts/kube-prometheus-stack/templates/prometheus/prometheus.yaml
index 6c0920058b70..3fd39c96b109 100644
--- a/charts/kube-prometheus-stack/templates/prometheus/prometheus.yaml
+++ b/charts/kube-prometheus-stack/templates/prometheus/prometheus.yaml
@@ -441,4 +441,10 @@ spec:
   tracingConfig:
 {{ toYaml .Values.prometheus.prometheusSpec.tracingConfig | indent 4 }}
 {{- end }}
+{{- with .Values.prometheus.prometheusSpec.additionalConfig }}
+  {{- tpl (toYaml .) $ | nindent 2 }}
+{{- end }}
+{{- with .Values.prometheus.prometheusSpec.additionalConfigString }}
+  {{- tpl . $ | nindent 2 }}
+{{- end }}
 {{- end }}
diff --git a/charts/kube-prometheus-stack/values.yaml b/charts/kube-prometheus-stack/values.yaml
index e9930ba86d30..00dd96683550 100644
--- a/charts/kube-prometheus-stack/values.yaml
+++ b/charts/kube-prometheus-stack/values.yaml
@@ -876,6 +876,14 @@ alertmanager:
     ## be considered available. Defaults to 0 (pod will be considered available as soon as it is ready).
     minReadySeconds: 0
 
+    ## Additional configuration which is not covered by the properties above. (passed through tpl)
+    additionalConfig: {}
+
+    ## Additional configuration which is not covered by the properties above.
+    ## Useful, if you need advanced templating inside alertmanagerSpec.
+    ## Otherwise, use alertmanager.alertmanagerSpec.additionalConfig (passed through tpl)
+    additionalConfigString: ""
+
   ## ExtraSecret can be used to store various data in an extra secret
   ## (use it for example to store hashed basic auth credentials)
   extraSecret:
@@ -3550,6 +3558,14 @@ prometheus:
     ## See https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#prometheustracingconfig
     tracingConfig: {}
 
+    ## Additional configuration which is not covered by the properties above. (passed through tpl)
+    additionalConfig: {}
+
+    ## Additional configuration which is not covered by the properties above.
+    ## Useful, if you need advanced templating inside alertmanagerSpec.
+    ## Otherwise, use prometheus.prometheusSpec.additionalConfig (passed through tpl)
+    additionalConfigString: ""
+
   additionalRulesForClusterRole: []
   #  - apiGroups: [ "" ]
   #    resources: