Company: MTZ
Filing Date: 2025-02-28
Form Type: S-3ASR
Source: 0001193125-25-042499
Chunk: 54

Company: MASTEC INC
Filing Date: 2025-02-28
Form: S-3ASR
Chunk 54
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such issue.

II-6

SIGNATURES Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Miami, State of Florida, on February 28, 2025.

| MASTEC, INC. |     |                              |
| By:          |     | /s/ José R. Mas              |
|              |     | José R. Mas                  |
|              |     | Chief Executive Officer      |
|              |     | -Principal Executive Officer |
| By:          |     | /s/ Paul DiMarco             |
|              |     | Paul DiMarco                 |
|              |     | Chief Financial Officer      |
|              |     | -Principal Financial Officer |

POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints José R. Mas, Paul DiMarco and Alberto de Cardenas his or her true and lawful attorneys-in-fact,each acting alone, with full powers of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any or all amendments, including any post-effective amendments, to this Registration Statement, and to file the same, with exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that said attorneys-in-factor their substitutes, each acting alone, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

| Signature           
 /s/ Jorge Mas       
 Jorge Mas           
 /s/ José R. Mas     
 José R. Mas         |     | Title                                                              
 Chairman of the Board of Directors                                 
 Chief Executive Officer and Director (Principal Executive Officer) |     | Date              
 February 28, 2025 
 February 28, 2025 |
|:--------------------|:----|:-------------------------------------------------------------------|:----|:------------------|
| /s/ Paul DiMarco    
 Paul DiMarco        |     | Chief Financial Officer (Principal Financial Officer)              |