diff --git a/cpp/src/arrow/acero/plan_test.cc b/cpp/src/arrow/acero/plan_test.cc
index 2cb03114de6..ceabeeaf099 100644
--- a/cpp/src/arrow/acero/plan_test.cc
+++ b/cpp/src/arrow/acero/plan_test.cc
@@ -757,6 +757,30 @@ TEST(ExecPlanExecution, DeclarationToSchema) {
   AssertSchemaEqual(expected_out_schema, actual_out_schema);
 }
 
+TEST(ExecPlanExecution, ProjectPreservesDirectFieldNullability) {
+  auto input_schema = schema({field("r", int64(), false), field("n", int64(), true)});
+  Declaration source(
+      "exec_batch_source",
+      ExecBatchSourceNodeOptions(input_schema, std::vector<compute::ExecBatch>{}));
+
+  auto direct = Declaration::Sequence(
+      {source,
+       {"project", ProjectNodeOptions({field_ref("r"), field_ref("n")}, {"r", "n"})}});
+  ASSERT_OK_AND_ASSIGN(auto direct_schema, DeclarationToSchema(direct));
+  AssertSchemaEqual(input_schema, direct_schema);
+
+  auto reordered = Declaration::Sequence(
+      {source,
+       {"project",
+        ProjectNodeOptions({field_ref("n"), field_ref("r"),
+                            call("add", {field_ref("r"), literal(int64_t{1})})},
+                           {"n", "renamed", "computed"})}});
+  ASSERT_OK_AND_ASSIGN(auto reordered_schema, DeclarationToSchema(reordered));
+  AssertSchemaEqual(schema({field("n", int64(), true), field("renamed", int64(), false),
+                            field("computed", int64(), true)}),
+                    reordered_schema);
+}
+
 TEST(ExecPlanExecution, DeclarationToReader) {
   auto basic_data = MakeBasicBatches();
   auto plan = Declaration::Sequence(
diff --git a/cpp/src/arrow/acero/project_node.cc b/cpp/src/arrow/acero/project_node.cc
index 188a2708835..71abdc2a035 100644
--- a/cpp/src/arrow/acero/project_node.cc
+++ b/cpp/src/arrow/acero/project_node.cc
@@ -67,14 +67,24 @@ class ProjectNode : public MapNode {
                           " doesn't match size of expressions " +
                           std::to_string(exprs.size())));
     }
+    const auto& input_schema = *inputs[0]->output_schema();
     FieldVector fields(exprs.size());
     int i = 0;
     for (auto& expr : exprs) {
       if (!expr.IsBound()) {
-        ARROW_ASSIGN_OR_RAISE(expr, expr.Bind(*inputs[0]->output_schema(),
-                                              plan->query_context()->exec_context()));
+        ARROW_ASSIGN_OR_RAISE(
+            expr, expr.Bind(input_schema, plan->query_context()->exec_context()));
       }
-      fields[i] = field(std::move(names[i]), expr.type()->GetSharedPtr());
+      bool nullable = true;
+      if (const auto* parameter = expr.parameter()) {
+        if (parameter->indices.size() == 1) {
+          int index = parameter->indices[0];
+          if (index >= 0 && index < input_schema.num_fields()) {
+            nullable = input_schema.field(index)->nullable();
+          }
+        }
+      }
+      fields[i] = field(std::move(names[i]), expr.type()->GetSharedPtr(), nullable);
       ++i;
     }
     return plan->EmplaceNode<ProjectNode>(plan, std::move(inputs),