Exhibit 99.1

FOR IMMEDIATE RELEASE

GLOBAL BRASS AND COPPER HOLDINGS, INC. ELECTS JOHN WASZ

PRESIDENT

Schaumburg, IL., September 9, 2013 Global Brass and Copper Holdings, Inc. (NYSE: BRSS) (“GBC” or the “Company”) today announced that on September 6, 2013, John Wasz was elected by the Board of Directors to the role of President, Global Brass and Copper Holdings, Inc. Mr. Wasz will also maintain his role as Chief Operating Officer of GBC and his role as President of GBC Metals, LLC (d\b\a Olin Brass). In his expanded role, Mr. Wasz will report to John Walker, the Company’s Chief Executive Officer, while all business segment Presidents will continue to report to Mr. Wasz.

“Since joining GBC, Mr. Wasz has driven transformative change within Olin Brass that has resulted in improved financial performance,” said John Walker, GBC’s Chief Executive Officer. “In this important new role, John will continue driving the strategy development process across the organization and working with the GBC business Presidents to expand and improve all of our operations, further allowing him to lead the execution of GBC’s vision and growth opportunities.”

Mr. Wasz has served as the Chief Operating Officer of GBC since January 2012 and as the President of GBC Metals, LLC (d\b\a Olin Brass) since 2010. Prior to joining GBC, he was the special advisor to the Chief Executive Officer of Aleris International, Inc. and served as Executive Vice President and President of Aleris Rolled Products North America, an aluminum manufacturer. Prior to that, he was Executive Vice President and President of Aflex, a manufacturer of industrial flexible hose, along with serving in several other management capacities at other companies throughout his career.

About Global Brass and Copper

Global Brass and Copper Holdings, Inc. through its wholly-owned principal operating subsidiary, Global Brass and Copper, Inc., is a leading, value-added converter, fabricator, distributor and processor of specialized copper and brass products in North America. We engage in metal melting and casting, rolling, drawing, extruding and stamping to fabricate finished and semi-finished alloy products from processed scrap, copper cathode and other refined metals. Our products include a wide range of sheet, strip, foil, rod, tube and fabricated metal component products that we sell under the Olin Brass, Chase Brass and A.J. Oster brand names. Our products are used in a variety of applications across diversified end markets, including the building and housing, munitions, automotive, transportation, coinage, electronics/electrical components, industrial machinery and equipment and general consumer end markets.

Cautionary Statement Concerning Forward-Looking Statements

This press release contains “forward-looking statements” that involve risks and uncertainties. You can identify forward-looking statements because they contain words such as “believes”, “expects”, “projects”, “may”, “would”, “should”, “seeks”, “approximately”, “intends”, “plans”, “estimates”, “anticipates” or similar expressions that relate to our strategy, plans or intentions. All statements the Company makes relating to its estimated and projected earnings, margins, costs, expenditures, cash flows, growth rates and financial results or to its expectations regarding future industry trends are forward-looking statements. In addition, the Company, through its senior management, from time to time make forward-looking public statements concerning its expected future operations and performance and other developments. These forward-looking statements are subject to known and unknown risks, uncertainties and other factors that may change at any time, and, therefore, the Company’s actual results may differ materially from those that it expected. The Company derives many of its forward-looking statements from its operating budgets and forecasts, which are based upon many detailed assumptions. While the Company believes that its assumptions are reasonable, it is very difficult to predict the impact of known factors, and, of course, it is impossible to anticipate all factors that could affect the Company’s actual results. Actual results may differ materially from these expectations due to various risks and uncertainties, including: the failure to maintain the Company’s balanced book approach which could cause increased volatility in the Company’s profitability and operating results and may result in significant losses; the loss in order volumes from any of the Company’s largest customers, which may reduce the Company’s sales volumes, revenues and cash flows; the disruption to the Company’s business if its customers shift their manufacturing offshore; the occurrence of any prolonged disruptions at or failures of the Company’s manufacturing facilities and equipment which could have a material adverse effect on its business, financial condition, results of operations and cash flows; and the failure to implement the Company’s business strategy, including its growth initiatives, could adversely affect its business, financial condition, results of operations or cash flows. More detailed information about these and other risks and uncertainties are contained in the Company’s filings with the Securities and Exchange Commission, including under “Risk Factors” and elsewhere in our Amendment No. 9 to Form S-1 Registration Statement filed with the Securities and Exchange Commission on May 22, 2013, in Item 1A “Risk Factors” and elsewhere in the Company’s Quarterly Report on From 10-Q for the quarter ended June 30, 2013 and in the Company’s other filings with the Securities and Exchange Commission. All forward-looking information in this press release is expressly qualified in its entirety by these cautionary statements. All forward-looking statements contained in this press release are based upon information available to the Company on the date of this press release. In addition, the matters referred to in the forward-looking statements contained in this press

release may not in fact occur. Accordingly, investors should not place undue reliance on those statements. The Company undertakes no obligation to publicly update or revise any forward-looking statement as a result of new information, future events or otherwise, except as otherwise required by law.