The 35-year-old Nigerian forward has signed a short-term deal with the Millers which will run until January.
Odemwingie arrives at the New York Stadium as a free agent after leaving Stoke City in the summer, linking up with new manager Kenny Jackett who only took the reins days ago.
"Rotherham and Bolton showed interest over the weekend. Time is not on my side at my age and the Championship is a bit closer to where I wish to be," he told Sky Sports News HQ.
"Thanks to Bolton for their interest in me but I'm really pleased to join Rotherham. Kenny showed some interest in me a few months ago and we have been in touch since then. I am pleased he got a job and he offered me a contract.
"My intuition said I'd be fine and that something would come along eventually. Playing well in the Premier League is still helping me now. Class is permanent, form is temporary, so I just need to find my form. All the movements are still there."
During his time in the Premier League, Odemwingie scored 37 goals in 129 appearances for the Potters, Baggies and Cardiff City.