Company: CGCT
Filing Date: 2025-05-01
Form Type: S-1MEF
Source: 0001104659-25-043663
Chunk: 1

Company: Cartesian Growth Corp III
Filing Date: 2025-05-01
Form: S-1MEF
Chunk 1
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 filed to register additional securities
for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration
statement number of the earlier effective registration statement for the same offering. x
333-284565

If this Form is a post-effective amendment filed
pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of
the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendment filed
pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of
the earlier effective registration statement for the same offering. ¨

Indicate by check mark whether the registrant is
a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See
the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and
“emerging growth company” in Rule 12b-2 of the Exchange Act.:

| Large accelerated filer ¨ |     | Accelerated filer ¨ |     | Non-accelerated filer x |     | Smaller reporting company x 
 Emerging growth company x   |

If an emerging growth company, indicate by check
mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting
standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ¨

The Registration Statement shall become effective upon filing with the U.S. Securities and Exchange Commission in accordance with Rule 462(b) under the Securities Act of 1933, as amended.

<div align='center'>EXPLANATORY NOTE</div>

This Registration Statement
on Form S-1 is being filed with respect to the registration of 4,600,000 additional units of Cartesian Growth Corporation III, a Cayman
Islands exempted company (the “Registrant”), each consisting of one Class A ordinary share, par value $0.0001 per share,
and one-third of one redeemable warrant (each whole warrant to purchase one Class A ordinary share of the Registrant), pursuant to Rule
462(b) under the Securities Act of 1933, as amended, and General Instruction V to Form S-1. Each whole warrant entitles