Rotary joint may refer to:

• Coupling, a mechanical device used to connect two shafts together at their ends for the purpose of transmitting power, including flexible couplings
• Rotary union, a coupling for passing fluid through a rotating joint
• Pivot joint, between animal bones
• Slip ring assembly, used to send electrical power and signals across a rotating connection
• Waveguide rotary joint, used to send microwave power and signals across a rotating connection
• Integrated Truss Structure § Solar alpha rotary joint, in the International Space Station