Jack Murray, aged 32, absconded from HMP Springhill Prison between midnight and 9.45 am on 15 May.
Murray is currently serving an 11 year sentence for a series of aggravated burglaries in the Southampton area, having been sentenced in 2015.
It is thought Murray may have changed his appearance and could now have shaved his head or dyed his hair darker.
Murray is white, 5ft 11ins tall, of medium build with brown eyes and he may be wearing glasses.
He has distinctive tattoos, including “ENGLAND” on his left forearm and a jester/skull on his left upper arm.
He is known to have links to Southampton and Poole.
Detective Sergeant Dale Price, based at Aylesbury police station, said: “If you see anyone that you think could be Jack, please get in touch immediately.
“We would urge members of the public not to approach him directly, just call us on 999.”
If you have any information relating to this case, please call 101 quoting reference ‘43180146077’, or contact Crimestoppers anonymously.