diff --git a/src/apm_cli/models/apm_package.py b/src/apm_cli/models/apm_package.py
index 31c42149..9de71844 100644
--- a/src/apm_cli/models/apm_package.py
+++ b/src/apm_cli/models/apm_package.py
@@ -305,7 +305,10 @@ def parse(cls, dependency_str: str) -> "DependencyReference":
         """
         if not dependency_str.strip():
             raise ValueError("Empty dependency string")
-        
+
+        # Decode percent-encoded characters (e.g., %20 for spaces in ADO project names)
+        dependency_str = urllib.parse.unquote(dependency_str)
+
         # Check for control characters (newlines, tabs, etc.)
         if any(ord(c) < 32 for c in dependency_str):
             raise ValueError("Dependency string contains invalid control characters")
@@ -557,12 +560,16 @@ def parse(cls, dependency_str: str) -> "DependencyReference":
                         raise ValueError(f"Invalid repository format: {repo_url}. Expected 'user/repo'")
                 
                 # Security: validate characters to prevent injection
+                # ADO project names may contain spaces
+                allowed_pattern = r'^[a-zA-Z0-9._\- ]+$' if is_ado_host else r'^[a-zA-Z0-9._-]+$'
                 for part in uparts:
-                    if not re.match(r'^[a-zA-Z0-9._-]+$', part.rstrip('.git')):
+                    if not re.match(allowed_pattern, part.rstrip('.git')):
                         raise ValueError(f"Invalid repository path component: {part}")
 
                 # Safely construct URL using detected host
-                github_url = urllib.parse.urljoin(f"https://{host}/", user_repo)
+                # Quote path components to handle spaces in ADO project names
+                quoted_repo = '/'.join(urllib.parse.quote(p, safe='') for p in uparts)
+                github_url = urllib.parse.urljoin(f"https://{host}/", quoted_repo)
                 parsed_url = urllib.parse.urlparse(github_url)
 
             # SECURITY: Validate that this is actually a supported Git host URL.
@@ -581,28 +588,31 @@ def parse(cls, dependency_str: str) -> "DependencyReference":
                 path = path[:-4]
             
             # Handle _git in parsed path for ADO URLs
-            path_parts = path.split("/")
+            # Decode percent-encoded path components (e.g., spaces in ADO project names)
+            path_parts = [urllib.parse.unquote(p) for p in path.split("/")]
             if '_git' in path_parts:
                 git_idx = path_parts.index('_git')
                 path_parts = path_parts[:git_idx] + path_parts[git_idx+1:]
-            
+
             # Validate path format based on host type
             is_ado_host = is_azure_devops_hostname(hostname)
             expected_parts = 3 if is_ado_host else 2
-            
+
             if len(path_parts) != expected_parts:
                 if is_ado_host:
                     raise ValueError(f"Invalid Azure DevOps repository path: expected 'org/project/repo', got '{path}'")
                 else:
                     raise ValueError(f"Invalid repository path: expected 'user/repo', got '{path}'")
-            
+
             # Validate all path parts contain only allowed characters
+            # ADO project names may contain spaces
+            allowed_pattern = r'^[a-zA-Z0-9._\- ]+$' if is_ado_host else r'^[a-zA-Z0-9._-]+$'
             for i, part in enumerate(path_parts):
                 if not part:
                     raise ValueError(f"Invalid repository format: path component {i+1} cannot be empty")
-                if not re.match(r'^[a-zA-Z0-9._-]+$', part):
+                if not re.match(allowed_pattern, part):
                     raise ValueError(f"Invalid repository path component: {part}")
-            
+
             repo_url = "/".join(path_parts)
             
             # If host not set via SSH or parsed parts, default to default_host()
@@ -613,8 +623,8 @@ def parse(cls, dependency_str: str) -> "DependencyReference":
         # Validate repo format based on host type
         is_ado_final = host and is_azure_devops_hostname(host)
         if is_ado_final:
-            # ADO format: org/project/repo (3 segments)
-            if not re.match(r'^[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+$', repo_url):
+            # ADO format: org/project/repo (3 segments, project may contain spaces)
+            if not re.match(r'^[a-zA-Z0-9._-]+/[a-zA-Z0-9._\- ]+/[a-zA-Z0-9._-]+$', repo_url):
                 raise ValueError(f"Invalid Azure DevOps repository format: {repo_url}. Expected 'org/project/repo'")
             # Extract ADO-specific fields
             ado_parts = repo_url.split('/')
@@ -655,7 +665,8 @@ def to_github_url(self) -> str:
         
         if self.is_azure_devops():
             # ADO format: https://dev.azure.com/org/project/_git/repo
-            return f"https://{host}/{self.ado_organization}/{self.ado_project}/_git/{self.ado_repo}"
+            project = urllib.parse.quote(self.ado_project, safe='')
+            return f"https://{host}/{self.ado_organization}/{project}/_git/{self.ado_repo}"
         else:
             # GitHub format: https://github.com/owner/repo
             return f"https://{host}/{self.repo_url}"
diff --git a/src/apm_cli/utils/github_host.py b/src/apm_cli/utils/github_host.py
index c186aaee..5ec20887 100644
--- a/src/apm_cli/utils/github_host.py
+++ b/src/apm_cli/utils/github_host.py
@@ -153,10 +153,11 @@ def build_ado_https_clone_url(org: str, project: str, repo: str, token: Optional
     Returns:
         str: HTTPS clone URL for Azure DevOps
     """
+    quoted_project = urllib.parse.quote(project, safe='')
     if token:
         # ADO uses PAT as password with empty username
-        return f"https://{token}@{host}/{org}/{project}/_git/{repo}"
-    return f"https://{host}/{org}/{project}/_git/{repo}"
+        return f"https://{token}@{host}/{org}/{quoted_project}/_git/{repo}"
+    return f"https://{host}/{org}/{quoted_project}/_git/{repo}"
 
 
 def build_ado_ssh_url(org: str, project: str, repo: str, host: str = "ssh.dev.azure.com") -> str:
@@ -177,12 +178,13 @@ def build_ado_ssh_url(org: str, project: str, repo: str, host: str = "ssh.dev.az
     Returns:
         str: SSH clone URL for Azure DevOps
     """
+    quoted_project = urllib.parse.quote(project, safe='')
     if host == "ssh.dev.azure.com":
         # Cloud format
-        return f"git@ssh.dev.azure.com:v3/{org}/{project}/{repo}"
+        return f"git@ssh.dev.azure.com:v3/{org}/{quoted_project}/{repo}"
     else:
         # Server format (user@host is optional, but commonly 'git@host')
-        return f"ssh://git@{host}/{org}/{project}/_git/{repo}"
+        return f"ssh://git@{host}/{org}/{quoted_project}/_git/{repo}"
 
 
 def build_ado_api_url(org: str, project: str, repo: str, path: str, ref: str = "main", host: str = "dev.azure.com") -> str:
@@ -202,8 +204,9 @@ def build_ado_api_url(org: str, project: str, repo: str, path: str, ref: str = "
         str: API URL for retrieving file contents
     """
     encoded_path = urllib.parse.quote(path, safe='')
+    quoted_project = urllib.parse.quote(project, safe='')
     return (
-        f"https://{host}/{org}/{project}/_apis/git/repositories/{repo}/items"
+        f"https://{host}/{org}/{quoted_project}/_apis/git/repositories/{repo}/items"
         f"?path={encoded_path}&versionDescriptor.version={ref}&api-version=7.0"
     )
 
diff --git a/tests/test_apm_package_models.py b/tests/test_apm_package_models.py
index fdbae36d..3496fa56 100644
--- a/tests/test_apm_package_models.py
+++ b/tests/test_apm_package_models.py
@@ -225,6 +225,43 @@ def test_parse_azure_devops_invalid_virtual_package(self):
         assert dep.is_virtual == False
         assert dep.repo_url == "myorg/myproject/myrepo"
     
+    def test_parse_azure_devops_project_with_spaces(self):
+        """Test that ADO project names with spaces are correctly parsed.
+        
+        Azure DevOps project names can contain spaces (e.g., 'My Project').
+        Users may specify them with %20 encoding or literal spaces (shell-quoted).
+        """
+        # Percent-encoded space in project name with _git segment
+        dep = DependencyReference.parse("dev.azure.com/myorg/My%20Project/_git/myrepo")
+        assert dep.host == "dev.azure.com"
+        assert dep.ado_organization == "myorg"
+        assert dep.ado_project == "My Project"
+        assert dep.ado_repo == "myrepo"
+        assert dep.is_azure_devops() == True
+        assert dep.repo_url == "myorg/My Project/myrepo"
+
+        # Literal space in project name (simplified format without _git)
+        dep = DependencyReference.parse("dev.azure.com/myorg/My Project/myrepo")
+        assert dep.host == "dev.azure.com"
+        assert dep.ado_organization == "myorg"
+        assert dep.ado_project == "My Project"
+        assert dep.ado_repo == "myrepo"
+        assert dep.is_azure_devops() == True
+
+        # Percent-encoded space in simplified format
+        dep = DependencyReference.parse("dev.azure.com/org/America%20Oh%20Yeah/repo")
+        assert dep.ado_project == "America Oh Yeah"
+        assert dep.ado_repo == "repo"
+
+        # to_github_url() should produce a properly percent-encoded URL
+        dep = DependencyReference.parse("dev.azure.com/myorg/My%20Project/_git/myrepo")
+        url = dep.to_github_url()
+        assert url == "https://dev.azure.com/myorg/My%20Project/_git/myrepo"
+
+        # Spaces should NOT be allowed in GitHub owner/repo names
+        with pytest.raises(ValueError):
+            DependencyReference.parse("github.com/my%20owner/repo")
+
     def test_parse_virtual_package_with_malicious_host(self):
         """Test that virtual packages with malicious hosts are rejected."""
         malicious_virtual_formats = [
diff --git a/tests/test_github_downloader.py b/tests/test_github_downloader.py
index afd73595..a85d4ad0 100644
--- a/tests/test_github_downloader.py
+++ b/tests/test_github_downloader.py
@@ -584,6 +584,38 @@ def test_build_repo_url_for_ado_ssh(self):
             # Should build ADO SSH URL (git@ssh.dev.azure.com:v3/org/project/repo)
             assert url.startswith('git@ssh.dev.azure.com:')
     
+    def test_build_ado_urls_with_spaces_in_project(self):
+        """Test that URL builders properly encode spaces in ADO project names."""
+        from apm_cli.utils.github_host import (
+            build_ado_https_clone_url,
+            build_ado_ssh_url,
+            build_ado_api_url,
+        )
+
+        # HTTPS clone URL with token
+        url = build_ado_https_clone_url("myorg", "My Project", "myrepo", token="tok")
+        assert "My%20Project" in url
+        assert "My Project" not in url
+        assert url == "https://tok@dev.azure.com/myorg/My%20Project/_git/myrepo"
+
+        # HTTPS clone URL without token
+        url = build_ado_https_clone_url("myorg", "My Project", "myrepo")
+        assert url == "https://dev.azure.com/myorg/My%20Project/_git/myrepo"
+
+        # SSH cloud URL
+        url = build_ado_ssh_url("myorg", "My Project", "myrepo")
+        assert "My%20Project" in url
+        assert url == "git@ssh.dev.azure.com:v3/myorg/My%20Project/myrepo"
+
+        # SSH server URL
+        url = build_ado_ssh_url("myorg", "My Project", "myrepo", host="ado.company.com")
+        assert "My%20Project" in url
+
+        # API URL
+        url = build_ado_api_url("myorg", "My Project", "myrepo", "path/file.md")
+        assert "My%20Project" in url
+        assert "My Project" not in url
+
     def test_build_repo_url_github_not_affected_by_ado_token(self):
         """Test that GitHub URL building uses GitHub token, not ADO token."""
         with patch.dict(os.environ, {