NioCorp Developments Ltd.

Item 1.01. Entry into a Material Definitive Agreement. The information contained in Item 3.03 below is incorporated herein by reference.

Item 3.03. Material Modification to Rights of Security Holders. As previously disclosed, the Board of Directors (the “Board”) of NioCorp Developments Ltd. (the “Company”) previously approved the Company’s limited-duration shareholder rights plan (the “Rights Plan”) as set forth in the Shareholder Rights Plan Agreement, dated as of November 21, 2025 (the “Original Rights Plan Agreement”), by and between the Company and Computershare Investor Services Inc., as rights agent (or any successor rights agent) (the “Rights Agent”). On April 6, 2026, following approval by the Company’s shareholders at the Annual Meeting (as defined below), the Company entered into an Amended and Restated Shareholder Rights Plan Agreement (the “Amended Rights Plan Agreement”), by and between the Company and the Rights Agent, which amends and restates the Original Shareholder Rights Plan Agreement in its entirety. The Rights Plan pursuant to the Original Rights Plan Agreement had an initial term of six months and would have expired on May 21, 2026, or earlier upon the redemption of the Rights (as defined within the Amended Rights Plan Agreement) or, provided that a Flip-In Event (as defined within the Amended Rights Plan Agreement) has not occurred, at such date or time as the Board may determine in its sole discretion (the “Expiration Time”). The Amended Rights Plan Agreement amends the definition of the Expiration Time of the Rights Plan to be 5:00 p.m. (Toronto time) on the date of the Company’s annual general meeting of shareholders held in 2027, or earlier upon the redemption of the Rights, or provided that a Flip-In Event has not occurred, at such date or time as the Board may determine in its sole discretion. The descriptions of the Rights and the Rights Plan are incorporated herein by reference to the description under the heading “Particulars of Matters to Be Acted Upon - VI - Approve Amendment and Extension of Company’s Shareholder Rights Plan” in the Company’s definitive proxy statement on Schedule 14A, filed with the Securities and Exchange Commission on February 25, 2026, and are qualified in their entirety by reference to the full text of the Amended Rights Plan Agreement, a copy of which is filed as Exhibit 4.1 to this Current Report on Form 8-K and is incorporated by reference herein.

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On April 6, 2026, at the Annual Meeting, the Company’s shareholders considered and approved the NioCorp Developments Ltd. Long Term Incentive Plan, as amended (the “2017 Amended Long-Term Incentive Plan”), which amended and restated the prior amendment and restatement of the NioCorp Developments Ltd. Long Term Incentive Plan that was approved by the Company’s shareholders on January 19, 2024 (the “2017 Long-Term Incentive Plan”). Under the 2017 Amended Long-Term Incentive Plan, the Board may in its discretion from time to time grant options (“Options”) to purchase Common Shares, without par value, of the Company (“Common Shares”), share units (in the form of restricted share units (“RSUs”) and performance share units (collectively with RSUs, “Share Units”)) and dividend equivalents to directors, employees and certain other service providers (as defined in the 2017 Amended Long-Term Incentive Plan) of the Company and affiliated entities selected by the Board. Subject to adjustment as provided in the 2017 Amended Long-Term Incentive Plan, the number of Common Shares available under the 2017 Amended Long-Term Incentive Plan for awards of (1) Options, (2) Share Units, and (3) dividend equivalents, will not exceed, in the aggregate, 11,300,000 Common Shares, minus, as of April 6, 2026, one Common Share for every one Common Share subject to an award granted under the 2017 Long-Term Incentive Plan after February 9, 2026 and before April 6, 2026. Such Common Shares may be shares of original issuance or treasury shares or a combination of the two. The finite share limit described above replaced the “evergreen” share limit that had previously been used the 2017 Long-Term Incentive Plan. Subject to the share counting rules of the 2017 Amended Long-Term Incentive Plan, the aggregate number of Common Shares available under the 2017 Amended Long-Term Incentive Plan will be reduced by one Common Share for every one Common Share subject to an award granted under the 2017 Amended Long-Term Incentive Plan. Under the 2017 Amended Long-Term Incentive Plan, subject to adjustment as provided in the 2017 Amended Long-Term Incentive Plan, the aggregate number of Common Shares actually issued or transferred by the Company upon the exercise of stock options intended to qualify as “incentive stock options” under Section 422 of the United States Internal Revenue Code will not exceed 11,300,000 Common Shares. The 2017 Amended Long-Term Incentive Plan also made the following other changes from the 2017 Long-Term Incentive Plan (in addition to certain non-material amendments of a housekeeping nature): implemented updated share counting and recycling provisions, including to provide as follows: (i) if any award under the 2017 Amended Long-Term Incentive Plan (in whole or in part) is cancelled or forfeited, expires, is settled for cash, or is unearned, the Common Shares subject to such award will, to the extent of such cancellation, forfeiture, expiration, cash ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── settlement, or unearned amount, again be available under the 2017 Amended Long-Term Incentive Plan; (ii) Common Shares withheld by the Company, tendered or otherwise used in payment of the exercise price of an Option will not be added (or added back, as applicable) to the aggregate number of Common Shares available under the 2017 Amended Long-Term Incentive Plan; (iii) Common Shares withheld by the Company, tendered or otherwise used to satisfy tax withholding with respect to awards will not be added (or added back, as applicable) to the aggregate number of Common Shares available under the 2017 Amended Long-Term Incentive Plan; and (iv) Common Shares reacquired by the Company on the open market or otherwise using cash proceeds from the exercise of Options will not be added (or added back, as applicable) to the aggregate number of Common Shares available under the 2017 Amended Long-Term Incentive Plan; ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── eliminated certain “evergreen” limitations on outstanding shares from time to time that could be reserved for issuance with respect to Share Units or to individual participants, as well as certain Toronto-Stock-Exchange-related limitations on shares issuable to insiders; included a limit on the annual compensation of the Company’s non-employee directors; updated the amendment provisions to more closely align with the rules of The Nasdaq Stock Market (“Nasdaq”); and clarified that the Company may take advantage of the applicable Nasdaq exemptions to shareholder approval of equity compensation plans. ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── The Board will generally be able to amend the 2017 Amended Long-Term Incentive Plan, subject to shareholder approval in certain circumstances as further described in the 2017 Amended Long-Term Incentive Plan. The foregoing description of the 2017 Amended Long-Term Incentive Plan is not complete and is in all respects qualified in its entirety by the actual provisions of the 2017 Amended Long-Term Incentive Plan, a copy of which is filed as Exhibit 10.1 hereto and is incorporated by reference herein.

Item 5.07 Submission of Matters to a Vote of Security Holders. On April 6, 2026, the Company held its Annual Meeting of Shareholders (the “Annual Meeting”). As of the record date for the Annual Meeting, there were 125,321,172 Common Shares issued and outstanding and entitled to vote, of which 56,773,600 Common Shares were present by proxy or in person at the Annual Meeting. The final results for each of the matters submitted to a vote of shareholders at the Annual Meeting are as follows and, pursuant to the requirements set out in subsection 11.3 of National Instrument 51-102, the Company gives notice of these results: Proposal One - To Set the Number of Directors for the Ensuing Year at Six. Votes For: 55,164,407 Votes Against: 1,609,193 Broker non-votes: 0 Proposal Two - Election of Directors. Nominee Votes FOR Votes WITHHELD Broker Non-Votes ────────────────────────────────────────────────────────────────────────────────── Mark A. Smith 27,749,599 1,206,180 27,817,821 Peter Oliver 25,418,410 3,537,369 27,817,821 Anthony W. Fulton 27,962,280 993,498 27,817,822 Nilsa Guerrero-Mahon 20,556,963 8,398,816 27,817,821 Michael G. Maselli 22,939,856 6,015,923 27,817,821 Dean C. Kehler 22,781,962 6,173,816 27,817,822 Proposal Three - Appointment of Deloitte & Touche LLP as Auditors of the Company for the Ensuing Year and Authorizing the Directors to Fix Their Remuneration. Votes For: 55,986,839 Votes Withheld: 786,761 Broker non-votes: 0 Proposal Four - Approval, on a Nonbinding, Advisory Basis, of the Compensation of the Company’s Named Executive Officers. Votes For: 22,285,849 Votes Against: 6,272,537 Abstentions: 397,390 Broker non-votes: 27,817,824 Proposal Five - Approval of the Amendment and Restatement of the NioCorp Developments Ltd. Long Term Incentive Plan. Votes For: 23,285,354 Votes Against: 5,326,885 Abstentions: 343,535 Broker non-votes: 27,817,826 Proposal Six - Approval of the Amendment and Extension of the Company’s Shareholder Rights Plan. Votes For: 23,942,251 Votes Against: 4,719,596 Abstentions: 293,931 Broker non-votes: 27,817,822