Activist Boniface Mwangi was Sunday picked up by unknown persons from his Machakos home.
His wife Njeri Mwangi confirmed the incident.
The latest development came barely 24 hours after Mwangi revealed plans to infiltrate and occupy the Standard Chartered Marathon, taking place on Sunday, October 27.
Security was enhanced at the event with major roads blocked for those participating.
Police revealed they were ready to address any form of threat from the planned protests and others.
Police in both uniforms and civilians were deployed to the event.
“We know him and his followers. They are courageous and can cause much damage to the event hence the move to deploy more,” said an officer aware of the issue.
In his post on Saturday evening, the activist urged his followers to show up for the marathon with attire opposing the Kenya Kwanza regime.
According to Njeri, the outspoken activist was picked up by unknown people on Sunday morning at around 7: 15 am.
"This morning at around 7.15, six uninformed people went to courage base and forcefully took my husband from the house. I have no idea who, why or where they have taken him," Boniface Mwangi's wife shared on social media.
Among other instructions, the activist urged his followers to adorn the national flag as part of their sports gear, wear hats with the national colours, record protest chants and share them online and bring placards with messages to President William Ruto.
“Will you show up to cheer friends at the Standard Chartered marathon? You are a crucial part of the race, your cheering will motivate and energise the athletes and help reform our country in the process.”
“This is how; adorn the national flag as part of your sports gear, wear hats with the national colours, wear a bandana with the message RutoMustGo, record protest chants and share online and bring a placard with your message to Ruto,” he said.
He told those who will participate in the event to post protest messages online and adopt the Kasongo song as their marathon chant and record any incidents of police brutality towards spectators and share them online.
“Stay calm and peaceful and have fun!” He said.