ONE Gas : Investor Update

Resilient and Reliable Energy

For a Better Tomorrow

INVESTOR UPDATE

August 30, 2021

Forward-Looking Statements

Statements contained in this presentation that include or refer to Company expectations, our business outlook, our future plans or predictions relating to any matters should be considered forward-looking statements that are covered by the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, the Securities Act of 1933 and the Securities and Exchange Act of 1934, each as amended. All statements, other than statements of historical facts, included in this presentation are forward-looking statements. Words such as "anticipates," "expects," "projects," "intends," "goals," "plans," "potential," "might," "believes," "target," "objective," "strategy," "opportunity," "pursue," "budgets," "outlook," "trends," "focus," "on schedule," "on track," "poised," "slated," "seeks," "estimates," "forecasts," "guidance," "scheduled," "continues," "may," "will," "would," "should," "could," "likely," and variations of such words and similar expressions are intended to identify such forward-looking statements. One should not place undue reliance on forward-looking statements. In addition, statements that refer to or are based on estimates, forecasts, projections, uncertain events or assumptions, including statements relating to market opportunities, future products or processes and the expected availability and benefits of such products or processes, and anticipated trends in our businesses or the markets relevant to them, including those developments relating to regulation and litigation trends and developments, also identify forward-looking statements. Such statements are based on management's expectations as of the date of this investor presentation, unless an earlier date is indicated, and involve many risks and uncertainties, known and unknown, that could cause actual results, performance or achievements to differ materially from those expressed or implied in these forward-looking statements.

It is important to note that the actual results could differ materially from those projected in such forward-looking statements. Important risks and uncertainties that could cause actual results to differ materially from the company's expectations include, but are not limited to, our ability to recover, manage and maintain costs; the concentration of our operations in Kansas, Oklahoma and Texas; regulatory or legislative changes in the jurisdictions in which we operate; the length and severity of unpredictable events, including, but not limited to, the COVID-19 pandemic, threatened terrorism, war or cyber-attacks or breaches, or extreme weather events, including those related to climate change; the competitive implications of alternative sources of energy and efforts to conserve energy; our competitive position, including, but not limited to our ability to secure competitive sourcing and pricing and our ability to compete with respect to expansion and infrastructure; the economic climate and our comparable economic position; our access to capital and the restrictions that result from our current capital arrangements; the effectiveness of our risk mitigation and compliance efforts; the uncertainties of any estimates or assumptions we use in our projections; our strategic and transactional efforts and future plans; and costs and uncertainties relating to our workforce, and other risks and uncertainties, including those that are set forth in ONE Gas' earnings release dated May 3, 2021, which is included as an exhibit to ONE Gas' Form 8-K furnished to the SEC on such date.

For additional information regarding these and other factors that could cause actual results to differ materially from such forward-looking statements, refer to ONE Gas' Securities and Exchange Commission filings., including the Company's most recent reports on Forms 10-K and 10-Q. Copies of the Company's Form 10-K,10-Q and 8-K reports may be obtained by visiting our "Investors" website under "Financials & Filings" at https://www.onegas.com/investors/financials-and-filings/quarterly-results/default.aspx or the SEC's website at www.sec.gov. Other unpredictable or unknown factors not discussed in this presentation could also have material adverse effects on the Company, its operations or the outcomes described in the forward- looking statements in this presentation or in the Company's filings with the Securities and Exchange Commission.

All future cash dividends discussed in this presentation are subject to the approval of the ONE Gas board of directors.

All references in this presentation to guidance are based on news releases issued on or before August 2, 2021, and are not being updated or affirmed by this presentation. ONE Gas does not undertake, and expressly disclaims any duty, to update any statement made in this presentation, whether as a result of new information, new developments or otherwise, except to the extent that disclosure may be required by law.

FORWARD LOOKING STATEMENTS | 2

VALUE CREATION STRATEGY

Sustainable Business Model

• Clear vision, mission, strategy and values-driven culture

Focused Business Strategy • 100% regulated natural gas distribution utility

• Conservative financial profile (investment-grade credit ratings)

Capital Horizon & Clarity	• 20+ year vintage pipeline replacement program
•	Leveraging technology to execute a risk-based approach to pipeline replacement

• Territory diversification - 3 states, multiple jurisdictions

Regulatory Construct • Comprehensive recovery mechanisms, ~ 93% of capital included in annual filings

• • Weather normalization
• High percentage of fixed charges for revenue recovery ~72%

Cash Flow Stability • Customer mix is predominantly residential ~ 92%

• Expense control through process and technology improvements

• Resilient and reliable energy delivery system

Competitive Advantage • Cost advantage over alternatives (electricity)

• • Strong growth in existing footprint
• Unwavering focus on safety of employees and communities and safe operation of our system

Safety & ESG • Committed to environmental, social and governance (ESG) stewardship and sustainability, including improved disclosures, data quality and reporting transparency

VALUE CREATION STRATEGY | 4

Mission, Vision, Strategy and Core Values

Mission - Why we exist

We deliver natural gas for a better tomorrow

Vision - What we want to be

To be a premier natural gas distribution company, creating exceptional value for our stakeholders

Strategy - How we do it

Becoming ONE:

• ONE in Responsibility - safety, reliability and compliance
• ONE in Value - customers, employees, investors and communities
• ONE in Industry - recognized leader, processes and productivity

Core Values - Our compass

SAFETY

We are committed to operating safely and in an environmentally responsible manner.

ETHICS

We are accountable to the highest ethical standards and are committed to compliance. Honesty, trust and integrity matter.

INCLUSION AND DIVERSITY

We embrace an inclusive and diverse culture that encourages collaboration. Every employee makes a difference and contributes to our success.

SERVICE

We provide exceptional service and make continuous improvements in our pursuit of excellence.

VALUE

We create value for all stakeholders, including our customers, employees, investors and communities.

VALUE CREATION STRATEGY | 5