document: Media playback is not supported on this device
  The 28-year-old Briton was fastest in the first of Saturday's two runs to climb from fourth to third and she held her position in the final run.
  Gold went to World Cup leader Jacqueline Lolling, with fellow German Tina Hermann finishing second.
  Yarnold's overall time of two minutes 36.08 seconds was 0.73secs behind Lolling.
  She returned to competition in December after taking a year out and will attempt to retain her Olympic title in South Korea next year.
  "This is where I want and need to be - and is a major stepping stone," Yarnold told BBC Sport.
  "It shows I've made the right decisions over the past couple of years and means more than I could ever explain.
  "I've had a few head and back issues recently and I physically wouldn't be here without the help of my physio and my family.
  "I am still dealing with some stuff but I am lucky with the team I have and that helps make me a stronger person and a better athlete."
  Yarnold's Great Britain team-mate Laura Deas finished 10th, with Donna Creighton 22nd.
  Nick Hope, BBC Olympic sports reporter:
  Despite all of Lizzy Yarnold's previous gold medals, World Championships bronze is a huge result both for her at the British skeleton team.
  She seemed to ease to Olympic, World Championship, European and World Cup titles between 2013 and 2015 - but, in truth, those successes left her exhausted.
  Although a year sabbatical has seen her return refreshed, younger rivals have emerged and the reappearance of dizzy spells - which first emerged in late 2014 - as well as the appearance of a new serious back problem, has made her comeback challenging than expected.
  However, despite just one World Cup podium finish this season Yarnold states she's now a "better slider" than before her break - and she has proved that when the big occasion arises she can still deliver.
  That is a crucial confidence boost for the British team, because with Laura Deas yet to rediscover the form that led to World Cup podiums last season and the GB men some way off he pace, Yarnold remains their only realistic hope of an Olympic skeleton medal in 2018.
summary: Olympic champion Lizzy Yarnold won bronze at the Skeleton World Championships in Germany.