Bannister's brother Rick became a quadriplegic after falling from a horse in April this year.
The accident has taken a heavy toll on Bannister and his family, and he has given away the game to spend more time with his brother.
"I obviously thought about it all year once my brother's accident happened, and you know, struggling with a full-time job and obviously my family commitments, something had to give," Bannister told AFL.com.au.
"I was dealing with a fair bit of stress. My main priorities were obviously my family and then work, so they came first."
Bannister isn't the only member of his family making sacrifices, with his mother quitting her job so that she can be by Rick's bedside daily.
"His mobility is improving slightly in his arms but his health as far as his swallowing is still the same as day one," Bannister said.
"He's still not able to eat or drink. That's probably the hardest part he struggles with. He hasn't had a drink for six months so that can be pretty demoralizing for him.
"He has days where he's just angry, depressed, doesn't speak to any of us, then he has days where he is more positive. It's just like a rollercoaster.
"My mum has quit her job to look after him during the daytime, so she sits by his hospital bed everyday just so he's got someone there to you know, scratch his face.
"He can't do too much at the moment. During the night-times, me and my brothers go in and mum can go home. I'm probably there during the week at least two or three of the nights, and on weekends, with umpiring you have to travel a fair bit interstate. It got to the stage where I was working full time, training at nights, seeing my brother on the other nights, going away interstate on weekends.
"I was starting to break down in the end. This way it will allow me to do my full-time job, which also involves a bit of travelling, and all my other time can be put back into family and my brother."
Bannister, who will turn 31 this month, tallied 67 games for Essendon and Carlton from 2001-09 before making the transition to umpiring.
After progressing through the grades, he made his debut as an AFL field umpire in 2012. He umpired in that season's finals series and ultimately officiated in 39 games.
"My last game was Melbourne v GWS in Sydney, so the atmosphere wasn't electric that day," Bannister said.
"I probably knew in my last three or four games, where I was dealing with a little bit of stress and I was rocking up to game day and a lot of the coaches were asking me 'are you ok?', and I kept saying I was because you don't want to give up or show that you're weak or anything.
"Every game I was just relieved to get into my car and drive home. I would just sit there and you'd kind of block it out when you're at the games, but I was struggling pretty badly outside of football. I kind of knew something had to change."
AFL umpiring director Jeff Gieschen lauded Bannister as "a trailblazer" for his effort to play and umpire at the highest level.
“Jordan had a unique skill set for an umpire, as a former player, and that made him successful and well-respected across the competition," Gieschen said.
“Within the list of senior umpires, he was highly respected by the players for his great feel for the game, was an excellent team man for other umpires and, despite his rapid improvement in the umpire ranks, was very humble natured.
“The tragic accident for his brother Ricky has been well-known within the football community, and Jordan’s commitment to his brother’s welfare as one of his primary carers can only be admired by everyone in the game and we fully respect and understand his decision to step back from umpiring and move on to the next stage of his life."
AFL media manager Patrick Keane had earlier tweeted:
Congrats @JordanBannister on his time as an AFL ump, now that he's stepping into retirement for work & to care for his brother. A good man.
— Patrick Keane (@AFL_PKeane) October 9, 2013
Bannister has been heavily involved in organising the Ricky Bannister Recover and Rebuild fundraiser, which will feature appearances by AFL identities in the Victory Room at Etihad Stadium on November 15.
Soon after his brother's accident, Bannister wrote a touching piece for the Back Page Lead website, in which he revealed in part:
"I umpired last week's Melbourne-GWS game in a fog, a blur. Instead of being filled with adrenalin at running out on the MCG, I felt weak, tired and burdened by an overwhelming sense of sadness.
"Five days earlier, I'd been told while I was in New York on a business trip that my older brother Rick had been thrown from his horse and had broken his neck.
"I was asleep in my hotel at 3am when the call came from one of my four brothers, Corey. He told me Ricky was in a coma and likely to be a quadriplegic. My world instantly came crashing down …
"It's so hard seeing the brother who protected me as a kid so vulnerable with countless tubes coming in and out of his body. Twelve days ago, he was a strong, fit man looking forward to his first born baby due in September. Now, he's fighting to stay alive.
"I just wish I could trade places with him and take all his pain away. I would take his place in a second …"
The AFL has advised that ex-St Kilda player Leigh Fisher, who umpired 15 games this season as a rookie-list umpire, has been promoted to the senior AFL list.
* To make a donation for the Ricky Bannister Recovery and Rehab fundraiser, visit www.rickybannister.com.au.