Season 1905/06 - two-year-old

Six starts: 1-0-1

Unplaced in his racing debut, Poseidon won at his second start as favourite by 4 lengths. Then sent to Melbourne, he had two starts but did not figure in the placings. Sent back to Sydney, Poseidon was off the board in the AJC Champagne Stakes. In his last two-year-old start he finished in a dead heat for third in the AJC Nursery Handicap, and was then sent out for a spell.

Season 1906/07 - three-year-old

14 starts: 11-3-0

Poseidon had an exemplary career as a three-year-old.

He began his three-year-old season with wins in two minor races, before winning the AJC Derby by three lengths, ahead of the two favourites. Just two days later, he raced against older competition for the first time in the AJC Metropolitan Handicap, finishing in second place to Solution (NZ).

Poseidon chalked up a string of wins in Melbourne. First came the VATC Eclipse Stakes in record time, then just two days later the Caulfield Cup in race record time, the VRC Victoria Derby, and finally the VRC Melbourne Cup.

After a spell over Christmas, Poseidon returned in the autumn and continued on his winning ways with wins in the VATC St Helier Stakes, VRC St Leger Stakes, and the VRC Loch Plate. He then finished second to Dividend in the three mile VRC Champion Stakes, before heading back to Sydney for the Autumn Racing Carnival.

In his two starts in the autumn, Poseidon won the AJC St Leger, but in his last start as a three-year-old, he finished second again to Dividend in the AJC Cumberland Stakes.

During his three-year-old season, Poseidon won approximately £12,000 in prize money.

Tom Clayton - Poseidon's regular jockey

Season 1907/08 - four-year-old

Twelve starts: 7-1-2

Poseidon continued on his winning way as a four-year-old.

At his first start back in the Rawson Stakes he finished third, but won at his next start, in the WFA AJC Spring Stakes (12-fur) at Randwick ahead of stable mate Apologue. At his second start Poseidon disappointed his backers with a poor third in the AJC Craven Plate, after Antonius had cannoned into him mid-race and knocked the wind out of him.

Moving back down to Melbourne for the Spring Carnival, Poseidon returned to form, winning the WFA VATC Eclipse Stakes at Caulfield on 16 October 1907, the Wednesday before the Caulfield Cup.

There were 16 starters in the Caulfield Cup in 1907, and after the start he was dropped towards the rear of the field. Jockey Tom Clayton waited to the half mile then set off on Poseidon. Poseidon raced around the field and dashed clear with a winning break, the Cup in his keeping. He had become the first horse to win consecutive Caulfield Cups.

On Derby Day, as 1-3 favourite, Poseidon won again beating Apologue in the VRC Melbourne Stakes.

Next was the Melbourne Cup, but as a result of his Caulfield Cup win, Poseidon was given a 10 lb penalty, and had to carry 10 stone 3 pounds (65 kg). The weight told, and Poseidon finished in eighth place with the win going to Apologue who carried only 7 st 9 lb (49 kg).

Poseidon's return to the track in 1908 was delayed by a minor leg problem. He bypassed the Melbourne Autumn Carnival but in a shortened Sydney program, won three of his four starts. His only failure was a fourth place to Tartan in the AJC Autumn Stakes.

Season 1908/09 - five-year-old

One unplaced start.

Poseidon returned as a five-year-old for one last campaign. After finishing fifth in the RRC Rawson Stakes, he pulled up sore. As he would require a long spell away from the track to recover, the decision was made to retire Poseidon to stud duties.