diff --git a/data_structures/binary_tree/transform_bst_sum_tree.py b/data_structures/binary_tree/transform_bst_sum_tree.py
new file mode 100644
index 000000000000..72237312d87a
--- /dev/null
+++ b/data_structures/binary_tree/transform_bst_sum_tree.py
@@ -0,0 +1,132 @@
+from __future__ import annotations
+
+
+class Node:
+    """
+    prints the inorder Traversal of transformed tree
+    >>> sum = 0
+    >>> root = Node(11)
+    >>> root.left = Node(2)
+    >>> root.right = Node(29)
+    >>> root.left.left = Node(1)
+    >>> root.left.right = Node(7)
+    >>> root.right.left = Node(15)
+    >>> root.right.right = Node(40)
+    >>> root.right.right.left = Node(35)
+    >>> printInorder(root)
+    1 2 7 11 15 29 35 40
+
+    >>> transformTree(root)
+
+    >>> printInorder(root)
+    139 137 130 119 104 75 40 0
+    """
+
+    def __init__(self, x) -> None:
+        self.data = x
+        self.left = None
+        self.right = None
+
+
+# Recursive function to transform a BST to sum tree.
+# This function traverses the tree in reverse inorder so
+# that we have visited all greater key nodes of the currently
+# visited node
+def transformTreeUtil(root) -> None:
+    """
+    Transform a binary tree into a sum tree.
+
+    Example:
+    >>> root = Node(11)
+    >>> root.left = Node(2)
+    >>> root.right = Node(29)
+    >>> transformTree(root)
+    >>> root.data
+    60
+    >>> root.left.data
+    31
+    >>> root.right.data
+    29
+    """
+
+    # Base case
+    if root == None:
+        return
+
+    # Recur for right subtree
+    transformTreeUtil(root.right)
+
+    # Update sum
+    global sum
+    sum = sum + root.data
+
+    # Store old sum in the current node
+    root.data = sum - root.data
+
+    # Recur for left subtree
+    transformTreeUtil(root.left)
+
+
+# A wrapper over transformTreeUtil()
+def transformTree(root) -> None:
+    """
+    Transform a binary tree into a sum tree.
+
+    Example:
+    >>> root = Node(11)
+    >>> root.left = Node(2)
+    >>> root.right = Node(29)
+    >>> transformTree(root)
+    >>> root.data
+    60
+    >>> root.left.data
+    31
+    >>> root.right.data
+    29
+    """
+
+    # sum = 0 #Initialize sum
+    transformTreeUtil(root)
+
+
+# A utility function to prindorder traversal of a
+# binary tree
+def printInorder(root):
+    """
+    Perform an inorder traversal of a binary tree and print the nodes.
+
+    Example:
+    >>> root = Node(11)
+    >>> root.left = Node(2)
+    >>> root.right = Node(29)
+    >>> printInorder(root)
+    2 11 29
+    """
+
+    if root == None:
+        return
+
+    printInorder(root.left)
+    print(root.data, end=" ")
+    printInorder(root.right)
+
+
+# Driver Program to test above functions
+if __name__ == "__main__":
+    sum = 0
+    root = Node(11)
+    root.left = Node(2)
+    root.right = Node(29)
+    root.left.left = Node(1)
+    root.left.right = Node(7)
+    root.right.left = Node(15)
+    root.right.right = Node(40)
+    root.right.right.left = Node(35)
+
+    print("Inorder Traversal of given tree")
+    printInorder(root)
+
+    transformTree(root)
+
+    print("\nInorder Traversal of transformed tree")
+    printInorder(root)