<SEC-DOCUMENT>0000950170-25-087892-index.html : 20250618
<SEC-HEADER>0000950170-25-087892.hdr.sgml : 20250618
<ACCEPTANCE-DATETIME>20250618161202
ACCESSION NUMBER:		0000950170-25-087892
CONFORMED SUBMISSION TYPE:	11-K
PUBLIC DOCUMENT COUNT:		3
CONFORMED PERIOD OF REPORT:	20241231
FILED AS OF DATE:		20250618
DATE AS OF CHANGE:		20250618

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FINANCIAL INSTITUTIONS INC
		CENTRAL INDEX KEY:			0000862831
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		ORGANIZATION NAME:           	02 Finance
		EIN:				160816610
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		11-K
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26481
		FILM NUMBER:		251057037

	BUSINESS ADDRESS:	
		STREET 1:		220 LIBERTY STREET
		CITY:			WARSAW
		STATE:			NY
		ZIP:			14569
		BUSINESS PHONE:		5857861100

	MAIL ADDRESS:	
		STREET 1:		220 LIBERTY STREET
		CITY:			WARSAW
		STATE:			NY
		ZIP:			14569
</SEC-HEADER>
<DOCUMENT>
<TYPE>11-K
<SEQUENCE>1
<FILENAME>fisi-11k-2024.12.31.htm
<DESCRIPTION>11-K
<TEXT>
Document 1 - file: fisi-11k-2024.12.31.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-23.1
<SEQUENCE>2
<FILENAME>fisi-ex23_1.htm
<DESCRIPTION>EX-23.1
<TEXT>
Document 2 - file: fisi-ex23_1.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>3
<FILENAME>img27068819_0.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 3 - file: img27068819_0.jpg

</DOCUMENT>
</SEC-DOCUMENT>