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.      )

Filed by the Registrant x                             Filed by a Party other than the Registrant ¨

Check the appropriate box:

¨ Preliminary Proxy Statement

¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨ Definitive Proxy Statement

x Definitive Additional Materials

¨ Soliciting Material Pursuant to § 240.14a-12

ESB Financial Corporation

(Name of Registrant as Specified in Its Charter)

N/A

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x No fee required.

¨ Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

(1) Title of each class of securities to which transaction applies:

(2) Aggregate number of securities to which transaction applies:

(3) Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4) Proposed maximum aggregate value of transaction:

(5) Total fee paid:

¨ Fee paid previously with preliminary materials.

¨ Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the form or schedule and the date of its filing.

(1) Amount previously paid:

(2) Form, schedule or registration statement no.:

(3) Filing party:

(4) Date filed:

January 5, 2015

***IMPORTANT REMINDER: PLEASE VOTE TODAY***

Dear Shareholder:

We have previously mailed you information relative to the Special Meeting of Shareholders of ESB Financial Corporation to be held on January 22, 2015.

According to our latest records we have not yet received your vote. The Special Meeting is now only a short time away. It is important that you sign and return the enclosed Voting Instruction Form today in order to make sure that your shares will be voted at the meeting in accordance with your desires. If you hold your shares in the name of a brokerage firm, your broker cannot vote your shares on these proposals unless they receive your specific instructions.

Your board of directors recommends that you vote FOR proposals 1, 2 and 3.

Your vote is important no matter how many shares you own.

Please sign and date the enclosed Voting Instruction Form (or follow the telephone & internet instructions) today. In the event that more than one vote is received from you, the one bearing the latest date will be counted, as it automatically revokes all prior proxies.

Thank you for your cooperation and continued support.

Sincerely,

Charlotte A. Zuschlag

President and CEO

*** Please Vote Today ***

600 Lawrence Avenue    ·    Ellwood City, PA 16117-1930    ·    724.758.5584    ·    724.758.0576 (Fax)