diff --git a/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/__init__.py b/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/__init__.py
new file mode 100644
index 000000000..e4782f24f
--- /dev/null
+++ b/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/__init__.py
@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+
+"""IBM FlashSystem iSCSI backend for Sunbeam storage."""
diff --git a/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/backend.py b/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/backend.py
new file mode 100644
index 000000000..520557736
--- /dev/null
+++ b/sunbeam-python/sunbeam/storage/backends/ibmflashsystemiscsi/backend.py
@@ -0,0 +1,84 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+
+"""FlashSystem iSCSI backend implementation using base step classes."""
+
+import logging
+from enum import StrEnum
+from typing import Annotated
+
+from pydantic import Field
+from rich.console import Console
+
+from sunbeam.core.manifest import StorageBackendConfig
+from sunbeam.storage.base import StorageBackendBase
+
+LOG = logging.getLogger(__name__)
+console = Console()
+
+
+class Protocol(StrEnum):
+    """Enumeration of valid protocol types."""
+
+    ISCSI = "iscsi"
+
+
+class IbmflashsystemiscsiConfig(StorageBackendConfig):
+    """Configuration model for FlashSystem iSCSI backend.
+
+    This model includes the essential static configuration options for
+    the backend. Additional backend configuration can be managed
+    dynamically through the charm.
+    """
+
+    # Mandatory connection parameters
+    san_ip: Annotated[
+        str, Field(description="Storage array management IP address or hostname.")
+    ]
+
+    # Optional backend configuration
+    protocol: Annotated[
+        Protocol | None,
+        Field(description="Protocol selector: iscsi."),
+    ] = None
+    flashsystem_iscsi_portid: Annotated[
+        int | None,
+        Field(description="Default iSCSI Port ID of FlashSystem. (Default port is 0.)"),  # noqa: E501
+    ] = None
+
+
+class IbmflashsystemiscsiBackend(StorageBackendBase):
+    """FlashSystem iSCSI backend implementation."""
+
+    backend_type = "ibmflashsystemiscsi"
+    display_name = "FlashSystem iSCSI"
+    generally_available = True
+
+    @property
+    def charm_name(self) -> str:
+        """Return the charm application name."""
+        return "cinder-volume-ibmflashsystemiscsi"
+
+    @property
+    def charm_channel(self) -> str:
+        """Return the default charm channel."""
+        return "latest/edge"
+
+    @property
+    def charm_revision(self) -> str | None:
+        """Return a pinned charm revision, if any."""
+        return None
+
+    @property
+    def charm_base(self) -> str:
+        """Return the target base for this charm."""
+        return "ubuntu@24.04"
+
+    @property
+    def supports_ha(self) -> bool:
+        """Whether this backend supports HA deployments."""
+        return False
+
+    def config_type(self) -> type[StorageBackendConfig]:
+        """Return the configuration model type for this backend."""
+        return IbmflashsystemiscsiConfig
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
index 80d3d8ef5..ab4136e32 100644
--- a/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
@@ -8,6 +8,9 @@
 from sunbeam.storage.backends.dellpowerstore.backend import DellPowerstoreBackend
 from sunbeam.storage.backends.dellsc.backend import DellSCBackend
 from sunbeam.storage.backends.hitachi.backend import HitachiBackend
+from sunbeam.storage.backends.ibmflashsystemiscsi.backend import (
+    IbmflashsystemiscsiBackend,
+)
 from sunbeam.storage.backends.purestorage.backend import PureStorageBackend
 
 
@@ -29,19 +32,28 @@ def dellsc_backend():
     return DellSCBackend()
 
 
+@pytest.fixture
+def ibmflashsystemiscsi_backend():
+    """Provide an IBM FlashSystem iSCSI backend instance."""
+    return IbmflashsystemiscsiBackend()
+
+
 @pytest.fixture
 def dellpowerstore_backend():
     """Provide a Dell PowerStore backend instance."""
     return DellPowerstoreBackend()
 
 
-@pytest.fixture(params=["hitachi", "purestorage", "dellsc", "dellpowerstore"])
+@pytest.fixture(
+    params=["hitachi", "purestorage", "dellsc", "ibmflashsystemiscsi", "dellpowerstore"]
+)
 def any_backend(request):
     """Parametrized fixture that provides each backend type."""
     backends = {
         "hitachi": HitachiBackend(),
         "purestorage": PureStorageBackend(),
         "dellsc": DellSCBackend(),
+        "ibmflashsystemiscsi": IbmflashsystemiscsiBackend(),
         "dellpowerstore": DellPowerstoreBackend(),
     }
     return backends[request.param]
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
index def51a0e8..7b7e2f87d 100644
--- a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
@@ -157,13 +157,18 @@ def backend(self, any_backend):
 
 
 def test_all_backends_have_unique_types(
-    hitachi_backend, purestorage_backend, dellsc_backend, dellpowerstore_backend
+    hitachi_backend,
+    purestorage_backend,
+    dellsc_backend,
+    ibmflashsystemiscsi_backend,
+    dellpowerstore_backend,
 ):
     """Test that all backends have unique type identifiers."""
     backends = [
         hitachi_backend,
         purestorage_backend,
         dellsc_backend,
+        ibmflashsystemiscsi_backend,
         dellpowerstore_backend,
     ]
     types = [b.backend_type for b in backends]
@@ -173,13 +178,18 @@ def test_all_backends_have_unique_types(
 
 
 def test_all_backends_have_unique_charm_names(
-    hitachi_backend, purestorage_backend, dellsc_backend, dellpowerstore_backend
+    hitachi_backend,
+    purestorage_backend,
+    dellsc_backend,
+    ibmflashsystemiscsi_backend,
+    dellpowerstore_backend,
 ):
     """Test that all backends have unique charm names."""
     backends = [
         hitachi_backend,
         purestorage_backend,
         dellsc_backend,
+        ibmflashsystemiscsi_backend,
         dellpowerstore_backend,
     ]
     charm_names = [b.charm_name for b in backends]
@@ -196,6 +206,7 @@ def test_all_backends_have_unique_charm_names(
         ("hitachi", "hitachi"),
         ("purestorage", "purestorage"),
         ("dellsc", "dellsc"),
+        ("ibmflashsystemiscsi", "ibmflashsystemiscsi"),
         ("dellpowerstore", "dellpowerstore"),
     ],
 )
@@ -211,6 +222,7 @@ def test_backend_types_match_expected(any_backend, backend_type, expected_type):
         ("hitachi", "cinder-volume-hitachi"),
         ("purestorage", "cinder-volume-purestorage"),
         ("dellsc", "cinder-volume-dellsc"),
+        ("ibmflashsystemiscsi", "cinder-volume-ibmflashsystemiscsi"),
         ("dellpowerstore", "cinder-volume-dellpowerstore"),
     ],
 )
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_ibmflashsystemiscsi.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_ibmflashsystemiscsi.py
new file mode 100644
index 000000000..f9bc6fa69
--- /dev/null
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_ibmflashsystemiscsi.py
@@ -0,0 +1,68 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+
+"""Tests for IBM FlashSystem iSCSI backend."""
+
+import pytest
+from pydantic import ValidationError
+
+from tests.unit.sunbeam.storage.backends.test_common import BaseBackendTests
+
+
+class TestIbmflashsystemiscsiBackend(BaseBackendTests):
+    """Tests for IBM FlashSystem iSCSI backend."""
+
+    @pytest.fixture
+    def backend(self, ibmflashsystemiscsi_backend):
+        """Provide IBM FlashSystem iSCSI backend instance."""
+        return ibmflashsystemiscsi_backend
+
+    def test_backend_type_is_ibmflashsystemiscsi(self, backend):
+        """Test that backend type is 'ibmflashsystemiscsi'."""
+        assert backend.backend_type == "ibmflashsystemiscsi"
+
+    def test_charm_name_is_ibmflashsystemiscsi_charm(self, backend):
+        """Test that charm name is cinder-volume-ibmflashsystemiscsi."""
+        assert backend.charm_name == "cinder-volume-ibmflashsystemiscsi"
+
+    def test_config_has_expected_fields(self, backend):
+        """Test that IBM FlashSystem iSCSI config exposes expected fields."""
+        fields = backend.config_type().model_fields
+        for field in ("san_ip", "protocol"):
+            assert field in fields, f"Expected field {field} not found in config"
+
+
+class TestIbmflashsystemiscsiConfigValidation:
+    """Test IBM FlashSystem iSCSI config validation behavior."""
+
+    def test_san_ip_is_required(self, ibmflashsystemiscsi_backend):
+        """Test that san-ip is required."""
+        config_class = ibmflashsystemiscsi_backend.config_type()
+        with pytest.raises(ValidationError):
+            config_class.model_validate(
+                {
+                    "protocol": "iscsi",
+                }
+            )
+
+    def test_protocol_rejects_invalid_value(self, ibmflashsystemiscsi_backend):
+        """Test that protocol rejects values other than iscsi."""
+        config_class = ibmflashsystemiscsi_backend.config_type()
+        with pytest.raises(ValidationError):
+            config_class.model_validate(
+                {
+                    "san-ip": "192.168.1.1",
+                    "protocol": "fc",
+                }
+            )
+
+    def test_protocol_accepts_iscsi(self, ibmflashsystemiscsi_backend):
+        """Test that protocol accepts iscsi."""
+        config_class = ibmflashsystemiscsi_backend.config_type()
+        config = config_class.model_validate(
+            {
+                "san-ip": "192.168.1.1",
+                "protocol": "iscsi",
+            }
+        )
+        assert config.protocol == "iscsi"