diff --git a/.changes/next-release/enhancement-configure-uooh8xep.json b/.changes/next-release/enhancement-configure-uooh8xep.json
new file mode 100644
index 0000000..05b6dbd
--- /dev/null
+++ b/.changes/next-release/enhancement-configure-uooh8xep.json
@@ -0,0 +1,5 @@
+{
+  "type": "enhancement",
+  "category": "configure",
+  "description": "Auto-detect project_id during grn configure by calling vServer /v1/projects with the given credentials and region"
+}
diff --git a/README.md b/README.md
index 1907aa3..ec39787 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,9 @@ GRN Client ID [None]: <your-client-id>
 GRN Client Secret [None]: <your-client-secret>
 Default region name [HCM-3]:
 Default output format [json]:
-Project ID (leave blank to auto-detect at runtime) [None]: pro-xxxxxxxx
+Project ID (leave blank to auto-detect) [None]:
+Fetching project_id from HCM-3...
+Auto-detected project_id: pro-xxxxxxxx
 ```
 
 **Method 3: Credentials file (manual)**
diff --git a/docs/configuration.md b/docs/configuration.md
index 9822b31..60eea29 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -13,12 +13,19 @@ GRN Client ID [None]: <your-client-id>
 GRN Client Secret [None]: <your-client-secret>
 Default region name [HCM-3]:
 Default output format [json]:
-Project ID (leave blank to auto-detect at runtime) [None]: pro-xxxxxxxx
+Project ID (leave blank to auto-detect) [None]:
+Fetching project_id from HCM-3...
+Auto-detected project_id: pro-xxxxxxxx
 ```
 
-`Project ID` is the VNG Cloud project UUID (e.g. `pro-e28d4501-...`). Each user may
-have multiple projects; pick the one you work with. Leave blank to let downstream
-tools (such as the GreenNode MCP Server) auto-detect at first call.
+`Project ID` is the VNG Cloud project UUID for the selected region (e.g.
+`pro-e28d4501-...`). Leave blank and the wizard calls the vServer API with
+your credentials to detect and save it. Each user has one project per region,
+so the detection is unambiguous.
+
+If auto-detect fails (network or auth error), the wizard prints a warning and
+leaves the field blank — downstream tools (such as the GreenNode MCP Server)
+can still auto-detect at first call.
 
 Credentials are obtained from the [VNG Cloud IAM Portal](https://hcm-3.console.vngcloud.vn/iam/) under Service Accounts.
 
diff --git a/go/cmd/configure/configure.go b/go/cmd/configure/configure.go
index 5d7e69e..a8afb74 100644
--- a/go/cmd/configure/configure.go
+++ b/go/cmd/configure/configure.go
@@ -48,7 +48,7 @@ func runConfigure(cmd *cobra.Command, args []string) {
 	clientSecret := promptWithDefault(reader, "Client Secret", maskCred(cfg.ClientSecret))
 	region := promptWithDefault(reader, "Default region name", cfg.Region)
 	output := promptWithDefault(reader, "Default output format", cfg.Output)
-	projectID := promptWithDefault(reader, "Project ID (leave blank to auto-detect at runtime)", cfg.ProjectID)
+	projectID := promptWithDefault(reader, "Project ID (leave blank to auto-detect)", cfg.ProjectID)
 
 	// If user entered masked value or empty, keep original
 	if clientID == maskCred(cfg.ClientID) || clientID == "" {
@@ -70,6 +70,22 @@ func runConfigure(cmd *cobra.Command, args []string) {
 		output = "json"
 	}
 
+	// Auto-detect project_id when left blank
+	if projectID == "" && clientID != "" && clientSecret != "" {
+		if endpoint, err := vserverEndpointForRegion(region); err != nil {
+			fmt.Fprintf(os.Stderr, "Warning: cannot determine vServer endpoint for region %q; leaving project_id blank.\n", region)
+		} else {
+			fmt.Printf("Fetching project_id from %s...\n", region)
+			detected, derr := detectProjectID(clientID, clientSecret, endpoint)
+			if derr != nil {
+				fmt.Fprintf(os.Stderr, "Warning: auto-detect failed: %v\nLeaving project_id blank.\n", derr)
+			} else {
+				fmt.Printf("Auto-detected project_id: %s\n", detected)
+				projectID = detected
+			}
+		}
+	}
+
 	writer := config.NewConfigFileWriter()
 
 	if err := writer.WriteCredentials(profile, clientID, clientSecret); err != nil {
diff --git a/go/cmd/configure/detect_project.go b/go/cmd/configure/detect_project.go
new file mode 100644
index 0000000..f806c59
--- /dev/null
+++ b/go/cmd/configure/detect_project.go
@@ -0,0 +1,77 @@
+package configure
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/vngcloud/greennode-cli/internal/auth"
+	"github.com/vngcloud/greennode-cli/internal/config"
+)
+
+// vserverEndpointForRegion returns the vServer base URL for a region,
+// looking it up in the REGIONS map.
+func vserverEndpointForRegion(region string) (string, error) {
+	r, ok := config.REGIONS[region]
+	if !ok {
+		return "", fmt.Errorf("unknown region: %s", region)
+	}
+	ep, ok := r["vserver_endpoint"]
+	if !ok {
+		return "", fmt.Errorf("no vserver_endpoint configured for region %s", region)
+	}
+	return ep, nil
+}
+
+// detectProjectTimeout is short — configure should fail fast, not hang the wizard.
+const detectProjectTimeout = 10 * time.Second
+
+type projectsResponse struct {
+	Projects []struct {
+		ProjectID string `json:"projectId"`
+	} `json:"projects"`
+}
+
+// detectProjectID fetches the caller's project from vServer /v1/projects
+// using the given credentials and region's vServer endpoint.
+//
+// Returns the first projectId. Each user is expected to have exactly one
+// project per region; returning the first is safe by that contract.
+func detectProjectID(clientID, clientSecret, vserverEndpoint string) (string, error) {
+	tm := auth.NewTokenManager(clientID, clientSecret)
+	token, err := tm.GetToken()
+	if err != nil {
+		return "", fmt.Errorf("authentication failed: %w", err)
+	}
+
+	req, err := http.NewRequest("GET", vserverEndpoint+"/v1/projects", nil)
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Authorization", "Bearer "+token)
+
+	httpClient := &http.Client{Timeout: detectProjectTimeout}
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("failed to fetch projects: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return "", fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
+	}
+
+	var parsed projectsResponse
+	if err := json.NewDecoder(resp.Body).Decode(&parsed); err != nil {
+		return "", fmt.Errorf("failed to parse response: %w", err)
+	}
+
+	if len(parsed.Projects) == 0 {
+		return "", fmt.Errorf("account has no project in this region")
+	}
+
+	return parsed.Projects[0].ProjectID, nil
+}