diff --git a/pkg/notification/client.go b/pkg/notification/client.go
index a4b02a1..a5738d7 100644
--- a/pkg/notification/client.go
+++ b/pkg/notification/client.go
@@ -304,6 +304,65 @@ func (c *Client) buildQueryParams(req *GetNotificationsRequest) string {
 	return result
 }
 
+// MarkSeen marks a notification as seen
+func (c *Client) MarkSeen(ctx context.Context, notificationID string) (*MarkSeenResponse, error) {
+	if c.config.EnableLogging && c.logger != nil {
+		c.logger.Debug("Marking notification as seen", map[string]interface{}{
+			"notification_id": notificationID,
+			"base_url":        c.config.BaseURL,
+		})
+	}
+
+	// Create HTTP request
+	url := fmt.Sprintf("%s/api/v1/notifications/%s/seen", c.config.BaseURL, notificationID)
+	httpReq, err := http.NewRequestWithContext(ctx, "PUT", url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create HTTP request: %w", err)
+	}
+
+	// Set headers
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("User-Agent", c.config.UserAgent)
+
+	// Send request
+	resp, err := c.httpClient.Do(httpReq)
+	if err != nil {
+		return nil, fmt.Errorf("HTTP request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	// Read response body
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	// Handle non-2xx status codes
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		// Try to parse error response
+		var errorResp NotificationErrorResponse
+		if json.Unmarshal(body, &errorResp) == nil && errorResp.Error != "" {
+			return nil, MapHTTPError(resp.StatusCode, errorResp.Error)
+		}
+		return nil, MapHTTPError(resp.StatusCode, string(body))
+	}
+
+	// Parse success response
+	var markSeenResp MarkSeenResponse
+	if err := json.Unmarshal(body, &markSeenResp); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal response: %w", err)
+	}
+
+	if c.config.EnableLogging && c.logger != nil {
+		c.logger.Info("Notification marked as seen successfully", map[string]interface{}{
+			"notification_id": notificationID,
+			"status":          markSeenResp.Status,
+		})
+	}
+
+	return &markSeenResp, nil
+}
+
 // shouldRetry determines if a request should be retried based on the error
 func (c *Client) shouldRetry(err error) bool {
 	switch e := err.(type) {
diff --git a/pkg/notification/entities.go b/pkg/notification/entities.go
index c5ba13a..74049f3 100644
--- a/pkg/notification/entities.go
+++ b/pkg/notification/entities.go
@@ -135,6 +135,8 @@ type NotificationItem struct {
 	Status      string            `json:"status"`
 	ScheduledAt int64             `json:"scheduled_at"`
 	IsScheduled bool              `json:"is_scheduled"`
+	Seen        bool              `json:"seen"`
+	SeenAt      int64             `json:"seen_at"`
 }
 
 // NotificationListResponse represents the response from getting notifications list
@@ -162,3 +164,13 @@ type GetNotificationsRequest struct {
 	Page      int    `json:"page,omitempty" valid:"optional"`
 	PerPage   int    `json:"per_page,omitempty" valid:"optional"`
 }
+
+// MarkSeenRequest represents the request for marking a notification as seen
+type MarkSeenRequest struct {
+	NotificationID string `json:"notification_id" valid:"required"`
+}
+
+// MarkSeenResponse represents the response from marking a notification as seen
+type MarkSeenResponse struct {
+	Status string `json:"status"`
+}
diff --git a/pkg/notification/interfaces.go b/pkg/notification/interfaces.go
index 627f411..8cde4cd 100644
--- a/pkg/notification/interfaces.go
+++ b/pkg/notification/interfaces.go
@@ -24,6 +24,9 @@ type NotificationService interface {
 	// GetNotifications retrieves a list of notifications
 	GetNotifications(ctx context.Context, req *GetNotificationsRequest) (*NotificationListResponse, error)
 
+	// MarkSeen marks a notification as seen
+	MarkSeen(ctx context.Context, notificationID string) (*MarkSeenResponse, error)
+
 	// Health checks if the notification service is available
 	Health(ctx context.Context) error
 
diff --git a/pkg/notification/sdk.go b/pkg/notification/sdk.go
index 0ff12fd..7c6eab2 100644
--- a/pkg/notification/sdk.go
+++ b/pkg/notification/sdk.go
@@ -79,6 +79,11 @@ func (s *SDK) GetNotifications(ctx context.Context, req *GetNotificationsRequest
 	return s.service.GetNotifications(ctx, req)
 }
 
+// MarkSeen marks a notification as seen
+func (s *SDK) MarkSeen(ctx context.Context, notificationID string) (*MarkSeenResponse, error) {
+	return s.service.MarkSeen(ctx, notificationID)
+}
+
 // NewBuilder creates a new notification builder for fluent API usage
 func (s *SDK) NewBuilder() Builder {
 	return s.service.(*Service).NewBuilder()
@@ -149,6 +154,12 @@ func (s *SDK) GetNotificationsByStatus(ctx context.Context, status string, page,
 	return s.GetNotifications(ctx, req)
 }
 
+// QuickMarkSeen marks a notification as seen (convenience method)
+func (s *SDK) QuickMarkSeen(ctx context.Context, notificationID string) error {
+	_, err := s.MarkSeen(ctx, notificationID)
+	return err
+}
+
 // Batch operations for sending multiple notifications
 
 // BatchRequest represents a batch notification request
diff --git a/pkg/notification/service.go b/pkg/notification/service.go
index d506db0..c1bf65c 100644
--- a/pkg/notification/service.go
+++ b/pkg/notification/service.go
@@ -109,6 +109,11 @@ func (s *Service) GetNotifications(ctx context.Context, req *GetNotificationsReq
 	return s.client.GetNotifications(ctx, req)
 }
 
+// MarkSeen marks a notification as seen
+func (s *Service) MarkSeen(ctx context.Context, notificationID string) (*MarkSeenResponse, error) {
+	return s.client.MarkSeen(ctx, notificationID)
+}
+
 // Health checks if the notification service is available
 func (s *Service) Health(ctx context.Context) error {
 	// Create a simple test request to check service availability