Taiclet, 60, is also former CEO of American Tower (AMT) - Get Report, the Boston communications real estate investment trust, and former president of Honeywell (HON) - Get Report Aerospace, a division of the Charlotte automotive and aerospace technology and products specialist.
Hewson, 66, becomes executive chairman. She's been president and CEO since 2013.
The executive transition "is being implemented strategically at a time when Lockheed Martin is financially strong and positioned well for the future," Hewson said.
Hewson was named CEO of the Year by Chief Executive magazine, a Top 10 "Businessperson of the Year" by Fortune magazine and one of the "World's 100 Most Powerful Women" by Forbes in 2018.
Lockheed Martin also named Frank A. St. John, 53, to the new post of chief operating officer. A more than 30-year veteran of the company, he is responsible for strategy, operations and financials at all of LMT's divisions.
Last week, the U.S. Senate Armed Services Committee awarded Lockheed Martin a $9.1 billion contract to produce 95 F-35 aircraft in the 2021 National Defense Authorization Act, the annual budget for the Department of Defense.
In April, the company reported stronger-than-expected first-quarter results, but with the coronavirus having an effect, the defense-and-aerospace icon lowered its 2020 revenue estimate.
The Bethesda, Md., company earned $1.72 billion, or $6.08 a share, in the quarter, up from $1.7 billion, or $5.99, in the year-earlier quarter. Revenue climbed 10% to $15.7 billion from $14.3 billion.
Analysts surveyed by Investing.com had forecast EPS of $5.78 on revenue of $15.1 billion.
Lockheed Martin shares at last check were falling 2.6% to $371.96.