    <SEC-DOCUMENT>0001104659-26-063598-index.html : 20260519
    <SEC-HEADER>0001104659-26-063598.hdr.sgml : 20260519
    <ACCEPTANCE-DATETIME>20260519091010
    ACCESSION NUMBER:		0001104659-26-063598
    CONFORMED SUBMISSION TYPE:	424B2
    PUBLIC DOCUMENT COUNT:		13
    FILED AS OF DATE:		20260519
    DATE AS OF CHANGE:		20260519

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			GOLUB CAPITAL BDC, Inc.
    		CENTRAL INDEX KEY:			0001476765
    		ORGANIZATION NAME:
    		EIN:				471893276
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			0930

    	FILING VALUES:
    		FORM TYPE:		424B2
    		SEC ACT:		1933 Act
    		SEC FILE NUMBER:	333-286240
    		FILM NUMBER:		26996146

    	BUSINESS ADDRESS:
    		STREET 1:		200 PARK AVENUE
    		STREET 2:		25TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10166
    		BUSINESS PHONE:		212.750.6060

    	MAIL ADDRESS:
    		STREET 1:		200 PARK AVENUE
    		STREET 2:		25TH FLOOR
    		CITY:			NEW YORK
    		STATE:			NY
    		ZIP:			10166

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	GOLUB CAPITAL INVESTMENT Corp
    		DATE OF NAME CHANGE:	20170511

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	Golub Capital BDC, Inc.
    		DATE OF NAME CHANGE:	20100414

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	Golub Capital BDC LLC
    		DATE OF NAME CHANGE:	20091113
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>424B2
    <SEQUENCE>1
    <FILENAME>gbdc-20260519x424b2.htm
    <DESCRIPTION>424B2
    <TEXT>
    Document 1 - file: gbdc-20260519x424b2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>2
    <FILENAME>gbdc-20260519.xsd
    <DESCRIPTION>EX-101.SCH
    <TEXT>
    Document 2 - file: gbdc-20260519.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>3
    <FILENAME>gbdc-20260519_def.xml
    <DESCRIPTION>EX-101.DEF
    <TEXT>
    Document 3 - file: gbdc-20260519_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>4
    <FILENAME>gbdc-20260519_lab.xml
    <DESCRIPTION>EX-101.LAB
    <TEXT>
    Document 4 - file: gbdc-20260519_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>5
    <FILENAME>gbdc-20260519_pre.xml
    <DESCRIPTION>EX-101.PRE
    <TEXT>
    Document 5 - file: gbdc-20260519_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>7
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 7 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>8
    <FILENAME>R2.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 8 - file: R2.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>9
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 9 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>12
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 12 - file: FilingSummary.html

    Document 12 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>14
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 14 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>15
    <FILENAME>0001104659-26-063598-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 15 - file: 0001104659-26-063598-xbrl.zip

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>16
    <FILENAME>gbdc-20260519x424b2_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: gbdc-20260519x424b2_htm.html

    Document 16 - RAW XML: gbdc-20260519x424b2_htm.xml

    </DOCUMENT>
    </SEC-DOCUMENT>