The prestigious award, his second after taking the title in 2015, caps a dream year on and off the bike for the South Australian.
In September, the road time trial star won his elusive first world championship in the event. He also won time trial stages at the Giro d'Italia and Vuelta a Espana and led the two Grand Tours.
That made him only the third Australian after Bradley McGee and Cadel Evans to hold the overall lead in the three Grand Tours - the Giro, Tour de France and Vuelta.
But it's also been a massive 2018 away from cycling for Dennis.
He was unable to attend Friday's cycling awards lunch in Melbourne because Dennis and wife Melissa have had their first child, a boy, and are in Europe. In February, Dennis married Melissa Hoskins, the retired world champion track cyclist.
Dennis, whose long-term project is to become an overall contender in the Grand Tours, overcame several years of frustration to win the time trial world title in Innsbruck, Austria.
A perennial favourite in the event, he was thwarted at the worlds and other major events such as the Olympics and Commonwealth Games by bad luck, crashing out at last year's world titles and the Rio Olympics, a broken aero bar robbing him of a probable silver medal.
Dennis also took out the men's road category.
World championship silver medallist Amanda Spratt won the women's road honour.
“It feels great," she said. "2018 was such a good year for me and it just feels nice to pick up that Elite Road Cyclist of the Year award amongst some pretty strong contenders.
“I think Australian women’s cycling is in such a strong position so I’m honoured to take the award."
Sarah Gigante and Lucas Plapp both had a big 2018 on the road and the track and deservedly took out both awards for best junior male and female on those surfaces.
Plapp took two world titles on the track and a silver at the junior men's road world ITT, Gigante a silver medal at the track worlds and Australian selection for the road world championships.
19-year-old Saya Sakakibara was awarded BMX cyclists of the year after finishing second overall on the UCI rankings and claiming her maiden World Cup win and four podium appearances. Logan Martin took the men’s award following 2018 World Cup and X-Games gold.
"It feels really amazing," Sakakibara said, I’m so humbled to be here, it’s my first ever year racing as an elite. I was fresh on the elite scene and had no idea what to expect."
The world record-breaking team pursuit squad narrowly beat world sprint champion Matthew Glaetzer to take out the men's track section. Stephanie Morton won the women's track category after a second straight worlds sprint sprint silver medal and dominating April’s Gold Coast Commonwealth Games with a triple gold medal haul in the team sprint (with McCulloch), keirin and sprint.
Visit the Cycling Australia website for a full list of winners.