diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ec7b30..b6e79be 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.18.2 (unreleased)
+
+- Added `best_objective_bound` method to `CpSolver` and `CpSolverSolutionCallback`
+
 ## 0.18.1 (2026-10-02)
 
 - Added support for breaks for routing
diff --git a/ext/or-tools/constraint.cpp b/ext/or-tools/constraint.cpp
index 74ae9f6..5d7bc2c 100644
--- a/ext/or-tools/constraint.cpp
+++ b/ext/or-tools/constraint.cpp
@@ -927,6 +927,7 @@ void init_constraint(Rice::Module& m) {
 
   Rice::define_class_under<CpSolverResponse>(m, "CpSolverResponse")
     .define_method("objective_value", &CpSolverResponse::objective_value)
+    .define_method("best_objective_bound", &CpSolverResponse::best_objective_bound)
     .define_method("num_conflicts", &CpSolverResponse::num_conflicts)
     .define_method("num_branches", &CpSolverResponse::num_branches)
     .define_method("wall_time", &CpSolverResponse::wall_time)
diff --git a/lib/or_tools/cp_solver.rb b/lib/or_tools/cp_solver.rb
index 99d482a..8e710e3 100644
--- a/lib/or_tools/cp_solver.rb
+++ b/lib/or_tools/cp_solver.rb
@@ -4,7 +4,7 @@ module ORTools
   class CpSolver
     extend Forwardable
 
-    def_delegators :@response, :objective_value, :num_conflicts, :num_branches, :wall_time
+    def_delegators :@response, :objective_value, :best_objective_bound, :num_conflicts, :num_branches, :wall_time
 
     def solve(model, observer = nil)
       @response = _solve(model, parameters, observer)
diff --git a/lib/or_tools/cp_solver_solution_callback.rb b/lib/or_tools/cp_solver_solution_callback.rb
index bf2b742..91721ed 100644
--- a/lib/or_tools/cp_solver_solution_callback.rb
+++ b/lib/or_tools/cp_solver_solution_callback.rb
@@ -17,6 +17,10 @@ def objective_value
       @response&.objective_value
     end
 
+    def best_objective_bound
+      @response&.best_objective_bound
+    end
+
     def stop_search
       @stopped = true
     end
diff --git a/test/constraint_test.rb b/test/constraint_test.rb
index fdad09d..b73c325 100644
--- a/test/constraint_test.rb
+++ b/test/constraint_test.rb
@@ -141,6 +141,7 @@ def test_optimization
       y = 3
       z = 5
     EOS
+    assert_equal 35, solver.best_objective_bound
   end
 
   # https://developers.google.com/optimization/cp/cryptarithmetic
diff --git a/test/solution_printer_test.rb b/test/solution_printer_test.rb
index e3129c0..9fb6cb3 100644
--- a/test/solution_printer_test.rb
+++ b/test/solution_printer_test.rb
@@ -11,6 +11,7 @@ def test_objective_solution_printer
     solver.parameters.enumerate_all_solutions = true
     solution_printer = ORTools::ObjectiveSolutionPrinter.new
     assert_nil solution_printer.objective_value
+    assert_nil solution_printer.best_objective_bound
 
     stdout, _ = capture_io do
       solver.solve(model, solution_printer)