Cover - shares	6 Months Ended
	Dec. 31, 2021	Feb. 04, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--06-30
Entity File Number	000-55710
Entity Registrant Name	NioCorp Developments Ltd.
Entity Central Index Key	0001512228
Entity Tax Identification Number	98-1262185
Entity Incorporation, State or Country Code	A1
Entity Address, Address Line One	7000 South Yosemite Street
Entity Address, Address Line Two	Suite 115
Entity Address, City or Town	Centennial
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80112
City Area Code	855
Local Phone Number	264-6267
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Elected Not To Use the Extended Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		264,903,954