QUANTA SERVICES INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. )

CHECK THE APPROPRIATE BOX:

Quanta Services, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

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2025 P R OX Y S TAT E M E N T

NOTICE OF ANNUAL MEETING

OF STOCKHOLDERS

Quanta Services, Inc.

2727 North Loop West

Houston, TX 77008 | (713)629-7600

TO BE HELD MAY 22, 2025

To our Stockholders:

The annual meeting of stockholders of Quanta Services, Inc. (“Quanta”) will be held at the company’s corporate headquarters, located at 2727 North Loop West, Houston, Texas 77008, on May 22, 2025, at 8:30 a.m. local time. At the meeting, you will be asked to consider and act upon the following matters, which are more fully described in the accompanying Proxy Statement:

Our stockholders of record at the close of business on April 2, 2025, are entitled to notice of, and to vote at, the annual meeting and any adjournments or postponements of the meeting.

By Order of the Board of Directors,

Matthew D. McCoy

Corporate Secretary

Houston, Texas

April 11, 2025

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON MAY 22, 2025:

The Notice, Proxy Statement and 2025 Annual Report to Stockholders are available atwww.proxydocs.com/PWR.

This summary highlights selected information about the items to be voted on at the 2025 annual meeting of stockholders (the “Annual Meeting”) of Quanta Services, Inc. (together with its subsidiaries, “Quanta” or the “Company”). This summary does not contain all of the information that you should consider in deciding how to vote. You should read the entire Proxy Statement carefully before voting.

2025 Annual Meeting of Stockholders

Where The Company’s corporate headquarters, located at 2727 North Loop West, Houston, Texas 77008

When May 22, 2025, at 8:30 a.m. local time

Record Date Our stockholders of record at the close of business on April 2, 2025, are entitled to notice of, and to vote at, the Annual Meeting and any adjournments or postponements of the meeting.

Annual Meeting Agenda and

Voting Recommendations

Stockholders are being asked to vote on four agenda matters:

Voting Your Shares

Your vote is important. Even if you plan to attend the Annual Meeting in person, the Board of Directors of Quanta (the “Board”) recommends that you cast your vote as soon as possible. Stockholders of record may vote by any of the below methods.

i

Proposal 1: Election of Directors

The Board of Directors unanimously recommends a vote FOR the election of each of the director nominees. u See page 1 for further information

Director Nominees

The table below provides summary information about each director nominee. Each director nominee is elected annually by a majority of votes cast.

ii

Snapshot of 2025 Director Nominees

Board Qualifications, Skills and Experience

The Board regularly reviews the desired qualifications, skills and experiences that it believes are appropriate to oversee Quanta’s business and long-term strategy. Attributes brought by director nominees include:

Corporate Governance Highlights

We are committed to strong governance standards, as evidenced by the key best practices below.

✓ Annual election of directors

✓ Majority voting standard for election of directors in uncontested elections

✓ Director resignation policy

✓ Holders of Quanta common stock vote as a single class on all matters

✓ Separate Independent Chairman of the Board and Chief Executive Officer

✓ Annual stockholder engagement

✓ Robust stock ownership requirements for directors and officers

iii

✓ Meaningful annual limit onnon-employee director compensation

✓ Code of Conduct that applies to all directors, officers and employees

✓ Robust oversight process of business strategy, risk management and corporate sustainability and responsibility matters

✓ Commitment to Board refreshment and composition aligned with the strategic direction of the Company

Proposal 2: Advisory Vote to Approve Executive Compensation

The Board of Directors unanimously recommends a vote FOR the advisory resolution approving Quanta’s executive compensation. u See page 30 for further information

Compensation Overview

Quanta completed another successful year in 2024, with strategic, operational and financial accomplishments throughout the Company. Quanta utilized its innovative approach to its infrastructure solutions, combined with its broad portfolio of services, to perform at a high level and produce superior operational and financial results. Specifically, the Company achieved many record financial results, including record annual revenues, net income attributable to common stock, and net cash provided by operating activities, as well as record remaining performance obligations and backlog as ofyear-end 2024.

Quanta continued to accomplish key strategic objectives in 2024 related to, among other things, the development and expansion of key service offerings and the Company’s position as a facilitator for its customers as they embark on significant efforts driven by load growth, the energy transition, technology advancements and grid resilience and security initiatives. Notably, Quanta completed the strategic acquisition of Cupertino Electric, Inc., a provider of electrical infrastructure solutions, including engineering, procurement, project management, construction and modularization services, to the technology, renewable energy and infrastructure and commercial industries, which provides Quanta with a highly synergisticlow-voltage electrical workforce and complementary customer base. Quanta believes its performance and these accomplishments are indicative of the resiliency of its business model and remains focused on delivering superior financial performance and returning value to its stockholders. Quanta is also focused on continuing its commitments to all stakeholders of the Company, including the safety of its workforce and responsible performance within communities in which it operates.

With respect to performance under the Company’s 2024 annual incentive plan, the overall achievement percentage was 78.7% of target performance, which was driven by significant year-over-year improvement in the earnings- and margin-based performance metrics, partially offset by below-threshold performance with respect to the safety performance improvement metric. Quanta also completed an exceptional 2022-2024 performance cycle that resulted in an achievement percentage of 189.9% of target performance under the 2022 long-term incentive plan, driven by continued improvement in the utilization of capital. Additionally, the performance targets and metrics included in the Company’s 2024 long-term incentive plan, which apply to the 2024-2026 performance cycle, continue to generally represent improvement over historical performance and prior targets and support Quanta’s strategic initiatives with respect to return on invested capital, efficient and sustainable usage of property and equipment and employee safety.

iv

2024 Target Compensation Mix

Quanta’s named executive officer (“NEO”) compensation is primarily comprised of base salary, short-term cash incentives and long-term equity incentives. Target award levels generally reflect competitive market levels and practices, with upside opportunity for performance above target levels, and performance measures are chosen to align the interests of executives with stockholders.

2024 Long-Term Incentive Plan Equity Mix

A significant portion of equity-based incentive awards (70% with respect to the Chief Executive Officer (“CEO”), Chief Operating Officer (“COO”) and President of Electric Power and 60% with respect to other NEOs) is tied to measurable Company performance over a 3-year performance period.

v

Elements of Executive Compensation

vi

Compensation Governance

We are committed to strong governance standards that ensure our executive compensation program is closely aligned with the interests of our stockholders and other stakeholders, as evidenced by the policies and practices described below.

What We Do

What We Don’t Do

Proposal 3: Ratification of the Appointment of Independent Registered Public Accounting Firm

The Board of Directors unanimously recommends a vote FOR ratification of the appointment of PricewaterhouseCoopers LLP as Quanta’s independent registered public accounting firm for fiscal year 2025. u See page 77 for further information

vii

Proposal 4: Approval of Amendment to Omnibus Equity Incentive Plan

The Board of Directors unanimously recommends a vote FOR approval of the amendment to the Quanta Services, Inc. 2019 Omnibus Equity Incentive Plan (as amended, the “2019 Omnibus Plan”) u See page 80 for further information

Summary of Amendment

Stockholders are being asked to approve an amendment to the 2019 Omnibus Plan. The 2019 Omnibus Plan was originally approved by the Board on March 21, 2019 and by Quanta’s stockholders on May 23, 2019. On March 21, 2025, the Board approved an amendment to the 2019 Omnibus Plan, subject to stockholder approval, which increases the number of shares of Quanta common stock that may be issued thereunder by 4,190,000 shares (the “Amendment”).

Quanta’s Grant Practices and Use of Equity-Based Compensation

2019 Omnibus Plan Best Practices

The 2019 Omnibus Plan includes features designed to protect stockholder interests and reflect our compensation and governance principles, as described below.

viii

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TABLE OF

CONTENTS

Board Recommendation✓ X