Rayner will join the Bombers under the alternative talent program, and qualifies as a rookie B listed player as he hasn't been registered in an Australian football competition for the past three years.
The 22-year-old was overlooked at the 2009 NAB AFL Draft after playing with TAC Cup side the Western Jets.
An Essendon fan, he left behind his football aspirations and turned to athletics, and last year won the men's 800m at the Australian National Championships.
"After I played for the Western Jets, I decided to go down the athletics path but recently the fire has been burning and I realised I wanted to play football again," Rayner said.
"I'm very thankful the opportunity came about to play with Essendon and I am looking forward to meeting my new teammates and getting started over the pre-season."
Essendon list manager Adrian Dodoro said losing the club's first two draft picks as part of the penalty for the supplements scandal had forced the Bombers to "think outside the box" with their draft selections.
"We were actually really close to placing him on our rookie list three to four years ago but he is a professional athlete and we think he’ll set some really high standards at this football club.
"We think he is completely worthy of the opportunity and we’re thrilled to have him at the club."
Rayner is the first player the Bombers have signed under the alternative talent program.
Twitter: @AFL_CalTwomey
