Kelly Johnson Design Acquired by Castle Design — Professional Services M&A

Castle Design, a St. Louis–based interior design firm founded in 2003, announced the acquisition of Kelly Johnson Design, a local architecture and design practice. The deal is structured as an add-on acquisition, with terms and deal value undisclosed. The transaction was announced to take effect on Jan. 1, expanding Castle Design’s footprint and bringing additional design talent under its leadership.

Castle Design is known for high-end, residential interior design, while Kelly Johnson Design adds complementary capabilities in architecture design and new construction. The combined offering is positioned to strengthen Castle Design’s ability to serve clients across the full residential design lifecycle, including projects where interior work and building design are closely coordinated. The move also reflects a strategic focus on growth in new construction, a segment founder Emily Castle expects to represent a meaningful share of the firm’s future business.

While no closing date beyond the Jan. 1 effective date was disclosed, the announcement emphasizes the integration of personnel and experience from both firms. The acquisition is expected to enhance Castle Design’s capacity to deliver end-to-end residential design services in Missouri, reinforcing its presence in the local professional services market.