Raila's departure comes hours before Miguna's expected arrival.
The former Prime Minister is expected to deliver lectures at the Cambridge University and Oxford University on Tuesday and Thursday, respectively.
According to his spokesman Dennis Onyango, Odinga will on Wednesday hold a meeting with the UK Minister for Africa at the Commonwealth Office.
The NASA leader will also meet Kenyans living in the UK at the Greenwood Lecture Theatres of King’s College.
He is accompanied to the UK trip by Nyando MP Jared Odoyo Okello.
Odinga's departure from the country interestingly coincides with the arrival of firebrand self-proclaimed National Resistance Movement General Miguna Miguna from Canada on Wednesday.
Already the government has warned Miguna not to expect any special treatment when he lands in the country.
Government spokesman Eric Kiraithe said the lawyer will have to comply with all the travel requirements warning that the law is clear and Miguna knows the procedure to be followed.