Cover - shares	6 Months Ended
	Jun. 30, 2023	Aug. 11, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Securities Act File Number	814-01162
Entity Registrant Name	Venture Lending & Leasing VIII, Inc.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	47-3919702
Entity Address, Address Line One	104 La Mesa Drive
Entity Address, Address Line Two	Suite 102
Entity Address, City or Town	Portola Valley
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94028
City Area Code	650
Local Phone Number	234-4300
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		100,000
Entity Central Index Key	0001642862
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2