The new dad, 32, is also encouraging other acts to follow his lead and show their support for the "Tik Tok" star, who sued her former mentor in a desperate bid to get out of a record deal with him.
Luke, real name Lukasz Gottwald, has vehemently denied Kesha's accusations and countersued for defamation.
Katy Perry and Lady GaGa have both been dragged into the legal spat - as both have worked with Dr. Luke - and now "Believer" singer Reynolds has added his name to the long list of Kesha supporters, insisting he won't be working with Luke until he drops defamation charges against the singer and releases her from her contract.
"I pledge to never work with Dr. Luke unless he drops his lawsuit against @KeshaRose and releases her of any contracts she has with him (publishing etc)," he tweets. "I ask all artists in our industry to make this same pledge. Please tweet about it and tag #boycottdrluke #FreeKesha."