The Election Commission issued the notice to Ramdev and organisers of the Yoga camp after scrutinising the video footage of the event.
"Ramdev and organisers of Yoga Mahotsav have been issued a show cause notice by the Delhi Election commission for using the platform for political activity without prior permission from the authorities," Delhi's Chief Electoral Officer Vijay Dev told reporters.
"The video footage of the event has been carefully examined by the officials and the organisers and Ramdev was found to be involved in violation of Model code," he said.
Asked why no notice was served on Modi, who addressed the gathering at the 'yoga mahotsav', Dev said no violation by the BJP leader was observed in the footage.
Modi had shared the dias with Ramdev and some other spiritual leaders and targeted Rahul Gandhi over his invocation of his family's sacrifices. Extending support to Modi, Ramdev had asked his supporters to help bring a "good leader" with "good intentions" to power.
North District Election officer Mona Sreeniwas told PTI that organisers had sought permission for holding a 'Yoga Mahotsav' and had not informed Election Commission that Modi would be attending it.
In his address, Modi had complimented Ramdev for organising the event in which technology was utilised in a big way. The programme was transmitted to 600 districts simultaneously.