v3.25.2
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2025
Aug. 05, 2025
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2025  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Document Quarterly Report true  
Document Transition Report false  
Entity Registrant Name Onex Direct Lending BDC Fund  
No Trading Symbol Flag true  
Entity Central Index Key 0001860424  
Current Fiscal Year End Date --12-31  
Securities Act File Number 814-01405  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 00-0000000  
Entity Address, Address Line One 930 Sylvan Avenue  
Entity Address, City or Town Englewood Cliffs  
Entity Address, State or Province NJ  
Entity Address, Postal Zip Code 07632  
City Area Code 201  
Local Phone Number 541-2121  
Title of 12(b) Security None  
Security Exchange Name NONE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   10,300,278