| Cover | Sep. 15, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 15, 2021 |
| Entity File Number | 1-36598 |
| Entity Registrant Name | CELLECTAR BIOSCIENCES, INC. |
| Entity Central Index Key | 0001279704 |
| Entity Tax Identification Number | 04-3321804 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 100 Campus Drive |
| Entity Address, City or Town | Florham Park |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07932 |
| City Area Code | 608 |
| Local Phone Number | 441-8120 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.00001 |
| Trading Symbol | CLRB |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
