Utility CenterPoint Energy Inc. said on Thursday it agreed to sell its natural gas distribution businesses in Arkansas and Oklahoma to Summit Utilities in a $2.15 billion cash deal that could help fund the seller’s transformation strategy.

The assets include 17,000 miles of pipelines in Arkansas and Oklahoma, serving more than half a million customers. The sale is expected to close by the end of 2021.

The sale could hasten CenterPoint’s efforts, launched last year, to become more of a pure-play utility as it aims to grow annual earnings by up to 8% while adding renewable energy to its portfolio.

Summit CEO Kurt Adams, meanwhile, said the deal represents an extension of an ongoing growth initiative in Arkansas and Oklahoma, providing important scale and added capacity....