  Light escaping from a gravitational potential suffers a redshift with
magnitude proportional to the depth of the potential. This "gravitational
redshift" is easily measurable in dense stars such as white dwarfs, but is much
weaker and has evaded unambiguous detection in main-sequence stars. I show that
the effect is directly measurable in the Gaia DR3 radial velocities (RVs) of
the components of wide binary stars. In a sample of $\sim$500 wide binaries
containing a solar-type main-sequence star and a red giant or red clump
companion, the apparent RV of the giant is on average $0.49 \pm 0.02 \,\, \rm
km\,s^{-1}$ lower than that of the main-sequence star. This owes primarily to
the giants' weaker gravitational fields and is in reasonably good agreement
with the value expected from general relativity.
