| Exhibit 21 | |||||
| DIRECT AND INDIRECT SUBSIDIARIES OF | |||||
| NorthWestern Energy Group, Inc. | |||||
As of December 31, 2025 | |||||
| Name | State of Jurisdiction of Incorporation or Limited Partnership | ||||
| NorthWestern Corporation | Delaware | ||||
| NorthWestern Energy Public Service Corporation | South Dakota | ||||
| The Clark Fork and Blackfoot, L.L.C. | Montana | ||||
| NorthWestern Services, LLC | Delaware | ||||
| Canadian-Montana Pipe Line Corporation | Canada | ||||
| Risk Partners Assurance, Ltd. | Bermuda | ||||
| Lodge Creek Pipelines, LLC | Nevada | ||||
| Willow Creek Gathering, LLC | Nevada | ||||
| Havre Pipeline Company, LLC | Texas | ||||
| NorthWestern Energy Solutions, Inc. | Delaware | ||||
| NorthWestern Great Falls Gas LLC | Montana | ||||
| NorthWestern Cut Bank Gas LCC | Montana | ||||
| Colstrip Property Holdings LLC | Montana | ||||
| NorthWestern Colstrip 222Av LLC | Montana | ||||
| NorthWestern Colstrip 370Pu LLC | Montana | ||||