Up to $250,000,000

Class A Common Stock

BlackSky Technology Inc. has entered into a sales agreement, or Sales Agreement, with Deutsche Bank Securities Inc. and Craig-Hallum Capital Group LLC, each a Sales Agent and together, the Sales Agents, dated as of May 22, 2026, relating to the sale of shares of our Class A common stock, or common stock, offered by this prospectus supplement and the accompanying base prospectus. In accordance with the terms of the Sales Agreement, we may offer and sell shares of our common stock, par value $0.0001 per share, having an aggregate offering price of up to $250,000,000 pursuant to this prospectus supplement from time to time through the Sales Agents, acting as our sales agents. This Sales Agreement replaces our prior sales agreement, dated December 12, 2025 with the Sales Agents, or the Prior Sales Agreement. No sales will be made pursuant to the Prior Sales Agreement subsequent to the date of this prospectus.

Our common stock is listed on The New York Stock Exchange, or the NYSE, under the symbol "BKSY." On May 20, 2026, the last reported sale price of our common stock on the NYSE was $45.58 per share.

Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus will be made in sales deemed to be an "at the market offering" as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended, or the Securities Act, including by means of ordinary brokers' transactions on the NYSE at market prices, in block transactions, or as otherwise agreed with the applicable Sales Agent, or by means of any other existing trading market for shares of our common stock or to or through a market maker other than on an exchange. We will submit orders to only one Sales Agent at a time relating to the sale of shares of our common stock under the Sales Agreement. The Sales Agents are not required to sell any specific amount of securities but will act as our sales agents using commercially reasonable efforts consistent with their normal trading and sales practices, on mutually agreed terms between the Sales Agents and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The compensation to the Sales Agents for sales of common stock sold pursuant to the Sales Agreement will be an amount up to 3.0% of the gross proceeds of any shares of common stock sold under the Sales Agreement. In connection with the sale of the common stock on our behalf, the Sales Agents may be deemed to be "underwriters" within the meaning of the Securities Act and the compensation of the Sales Agents may be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to the Sales Agents with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended, or the Exchange Act.