Company: TEN-PE
Filing Date: 2025-04-30
Form Type: 6-K
Source: 0001193125-25-105752
Chunk: 0

Company: TSAKOS ENERGY NAVIGATION LTD
Filing Date: 2025-04-30
Form: 6-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of April 2025

Commission File Number 001-31236

### TSAKOS ENERGY NAVIGATION LIMITED
(Translation of registrant’s name into English)

367 Syngrou Avenue, 175 64 P. Faliro, Athens, Greece

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

TSAKOS ENERGY NAVIGATION LIMITED FORM 6-K EXHIBIT INDEX

| Exhibit 
 Number  |     | Exhibit Title                                                  |
| 99.1    |     | Proxy Statement for the 2025 Annual Meeting of Shareholders    |
| 99.2    |     | Form of Proxy Card for the 2025 Annual Meeting of Shareholders |
| 99.3    |     | Notice of Internet Availability of Proxy Materials             |
| 99.4    |     | 2024 Audited Financial Statements                              |

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. Date: April 30, 2025

| TSAKOS ENERGY NAVIGATION LIMITED |     |                                       |
| By:                              |     | /s/ George Saroglou                   |
|                                  |     | George Saroglou                       |
|                                  |     | President and Chief Operating Officer |