diff --git a/command/commands.go b/command/commands.go
index 6b9f5c89e7..f6aad476d1 100644
--- a/command/commands.go
+++ b/command/commands.go
@@ -347,6 +347,11 @@ func initCommands(ui, serverCmdUi cli.Ui, runOpts *RunOptions) {
 				BaseCommand: getBaseCommand(),
 			}, nil
 		},
+		"namespace patch": func() (cli.Command, error) {
+			return &NamespacePatchCommand{
+				BaseCommand: getBaseCommand(),
+			}, nil
+		},
 		"namespace delete": func() (cli.Command, error) {
 			return &NamespaceDeleteCommand{
 				BaseCommand: getBaseCommand(),
diff --git a/command/namespace.go b/command/namespace.go
index 89cf2e0296..702395753d 100644
--- a/command/namespace.go
+++ b/command/namespace.go
@@ -36,6 +36,10 @@ Usage: vault namespace <subcommand> [options] [args]
 
       $ vault namespace create
 
+  Patch an existing namespace:
+
+      $ vault namespace patch
+
   Delete an existing namespace:
 
       $ vault namespace delete
diff --git a/command/namespace_create.go b/command/namespace_create.go
index 80ce589f96..7d1f52fa8c 100644
--- a/command/namespace_create.go
+++ b/command/namespace_create.go
@@ -15,6 +15,8 @@ var (
 
 type NamespaceCreateCommand struct {
 	*BaseCommand
+
+	flagCustomMetadata map[string]string
 }
 
 func (c *NamespaceCreateCommand) Synopsis() string {
@@ -43,7 +45,18 @@ Usage: vault namespace create [options] PATH
 }
 
 func (c *NamespaceCreateCommand) Flags() *FlagSets {
-	return c.flagSet(FlagSetHTTP | FlagSetOutputField | FlagSetOutputFormat)
+	set := c.flagSet(FlagSetHTTP | FlagSetOutputField | FlagSetOutputFormat)
+
+	f := set.NewFlagSet("Command Options")
+	f.StringMapVar(&StringMapVar{
+		Name:    "custom-metadata",
+		Target:  &c.flagCustomMetadata,
+		Default: map[string]string{},
+		Usage: "Specifies arbitrary key=value metadata meant to describe a namespace." +
+			"This can be specified multiple times to add multiple pieces of metadata.",
+	})
+
+	return set
 }
 
 func (c *NamespaceCreateCommand) AutocompleteArgs() complete.Predictor {
@@ -80,7 +93,11 @@ func (c *NamespaceCreateCommand) Run(args []string) int {
 		return 2
 	}
 
-	secret, err := client.Logical().Write("sys/namespaces/"+namespacePath, nil)
+	data := map[string]interface{}{
+		"custom_metadata": c.flagCustomMetadata,
+	}
+
+	secret, err := client.Logical().Write("sys/namespaces/"+namespacePath, data)
 	if err != nil {
 		c.UI.Error(fmt.Sprintf("Error creating namespace: %s", err))
 		return 2
diff --git a/command/namespace_patch.go b/command/namespace_patch.go
new file mode 100644
index 0000000000..6f5b8390f1
--- /dev/null
+++ b/command/namespace_patch.go
@@ -0,0 +1,137 @@
+package command
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/posener/complete"
+
+	"github.com/mitchellh/cli"
+)
+
+var (
+	_ cli.Command             = (*NamespacePatchCommand)(nil)
+	_ cli.CommandAutocomplete = (*NamespacePatchCommand)(nil)
+)
+
+type NamespacePatchCommand struct {
+	*BaseCommand
+
+	flagCustomMetadata       map[string]string
+	flagRemoveCustomMetadata []string
+}
+
+func (c *NamespacePatchCommand) Synopsis() string {
+	return "Patch an existing namespace"
+}
+
+func (c *NamespacePatchCommand) Help() string {
+	helpText := `
+Usage: vault namespace patch [options] PATH
+
+  Patch an existing namespace. The namespace patched will be relative to the
+  namespace provided in either the VAULT_NAMESPACE environment variable or
+  -namespace CLI flag.
+
+  Patch an existing child namespace by adding and removing custom-metadata (e.g. ns1/):
+
+      $ vault namespace patch ns1 -custom-metadata=foo=abc -remove-custom-metadata=bar
+
+  Patch an existing child namespace from a parent namespace (e.g. ns1/ns2/):
+
+      $ vault namespace patch -namespace=ns1 ns2 -custom-metadata=foo=abc
+
+` + c.Flags().Help()
+
+	return strings.TrimSpace(helpText)
+}
+
+func (c *NamespacePatchCommand) Flags() *FlagSets {
+	set := c.flagSet(FlagSetHTTP | FlagSetOutputField | FlagSetOutputFormat)
+
+	f := set.NewFlagSet("Command Options")
+	f.StringMapVar(&StringMapVar{
+		Name:    "custom-metadata",
+		Target:  &c.flagCustomMetadata,
+		Default: map[string]string{},
+		Usage: "Specifies arbitrary key=value metadata meant to describe a namespace." +
+			"This can be specified multiple times to add multiple pieces of metadata.",
+	})
+
+	f.StringSliceVar(&StringSliceVar{
+		Name:    "remove-custom-metadata",
+		Target:  &c.flagRemoveCustomMetadata,
+		Default: []string{},
+		Usage:   "Key to remove from custom metadata. To specify multiple values, specify this flag multiple times.",
+	})
+
+	return set
+}
+
+func (c *NamespacePatchCommand) AutocompleteArgs() complete.Predictor {
+	return complete.PredictNothing
+}
+
+func (c *NamespacePatchCommand) AutocompleteFlags() complete.Flags {
+	return c.Flags().Completions()
+}
+
+func (c *NamespacePatchCommand) Run(args []string) int {
+	f := c.Flags()
+
+	if err := f.Parse(args); err != nil {
+		c.UI.Error(err.Error())
+		return 1
+	}
+
+	args = f.Args()
+	switch {
+	case len(args) < 1:
+		c.UI.Error(fmt.Sprintf("Not enough arguments (expected 1, got %d)", len(args)))
+		return 1
+	case len(args) > 1:
+		c.UI.Error(fmt.Sprintf("Too many arguments (expected 1, got %d)", len(args)))
+		return 1
+	}
+
+	namespacePath := strings.TrimSpace(args[0])
+
+	client, err := c.Client()
+	if err != nil {
+		c.UI.Error(err.Error())
+		return 2
+	}
+
+	data := make(map[string]interface{})
+	customMetadata := make(map[string]interface{})
+
+	for key, value := range c.flagCustomMetadata {
+		customMetadata[key] = value
+	}
+
+	for _, key := range c.flagRemoveCustomMetadata {
+		// A null in a JSON merge patch payload will remove the associated key
+		customMetadata[key] = nil
+	}
+
+	data["custom_metadata"] = customMetadata
+
+	secret, err := client.Logical().JSONMergePatch(context.Background(), "sys/namespaces/"+namespacePath, data)
+	if err != nil {
+		c.UI.Error(fmt.Sprintf("Error patching namespace: %s", err))
+		return 2
+	}
+
+	if secret == nil || secret.Data == nil {
+		c.UI.Error(fmt.Sprintf("No namespace found: %s", err))
+		return 2
+	}
+
+	// Handle single field output
+	if c.flagField != "" {
+		return PrintRawField(c.UI, secret, c.flagField)
+	}
+
+	return OutputSecret(c.UI, secret)
+}
diff --git a/helper/namespace/namespace.go b/helper/namespace/namespace.go
index b196047121..93d68622de 100644
--- a/helper/namespace/namespace.go
+++ b/helper/namespace/namespace.go
@@ -12,9 +12,9 @@ import (
 type contextValues struct{}
 
 type Namespace struct {
-	ID             string            `json:"id"`
-	Path           string            `json:"path"`
-	CustomMetadata map[string]string `json:"custom_metadata"`
+	ID             string            `json:"id" mapstructure:"id"`
+	Path           string            `json:"path" mapstructure:"path"`
+	CustomMetadata map[string]string `json:"custom_metadata" mapstructure:"custom_metadata"`
 }
 
 func (n *Namespace) String() string {
diff --git a/sdk/helper/custommetadata/custom_metadata.go b/sdk/helper/custommetadata/custom_metadata.go
index af8d4c163a..7d4ff8763d 100644
--- a/sdk/helper/custommetadata/custom_metadata.go
+++ b/sdk/helper/custommetadata/custom_metadata.go
@@ -3,6 +3,8 @@ package custommetadata
 import (
 	"fmt"
 
+	"github.com/mitchellh/mapstructure"
+
 	"github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/go-secure-stdlib/strutil"
 )
@@ -16,6 +18,31 @@ const (
 	validationErrorPrefix = "custom_metadata validation failed"
 )
 
+// Parse is used to effectively convert the TypeMap
+// (map[string]interface{}) into a TypeKVPairs (map[string]string)
+// which is how custom_metadata is stored. Defining custom_metadata
+// as a TypeKVPairs will convert nulls into empty strings. A null,
+// however, is essential for a PATCH operation in that it signals
+// the handler to remove the field. The filterNils flag should
+// only be used during a patch operation.
+func Parse(raw map[string]interface{}, filterNils bool) (map[string]string, error) {
+	customMetadata := map[string]string{}
+	for k, v := range raw {
+		if filterNils && v == nil {
+			continue
+		}
+
+		var s string
+		if err := mapstructure.WeakDecode(v, &s); err != nil {
+			return nil, err
+		}
+
+		customMetadata[k] = s
+	}
+
+	return customMetadata, nil
+}
+
 // Validate will perform input validation for custom metadata.
 // CustomMetadata should be arbitrary user-provided key-value pairs meant to
 // provide supplemental information about a resource. If the key count