After showing some promise in his early races he emerged as a top-class stayer in the autumn on 1979, winning the Geoffrey Freer Stakes, Irish St. Leger and Prix Royal-Oak.

[4] Lady Beaverbrook was considered an eccentric character[5] who gave most of her horses names consisting of one word with seven letters (Bustino, Terimon, Boldboy, Niniski, Mystiko, Petoski), as this was the most common form for Derby winners.

On 6 June, Ninisiki started an 80/1 outsider for the 200th running of the Derby Stakes over one and a half miles at Epsom Downs Racecourse and finished ninth of the twenty-three runners behind his stablemate Troy.

He took the lead approaching the final furlong and drew away in the closing stages to win by three lengths from the four-year-old M-Lolshan, the winner of the Irish St. Leger and Grosser Preis von Baden.

[8] Two weeks later Niniski started 7/5 favourite for the Prix Royal Oak, France's equivalent of the St Leger, run over 3100 metres at Longchamp Racecourse.

[8] On his four-year-old debut, Niniski was brought back in distance for the John Porter Stakes over one and a half miles at Newbury in April and started at odds of 2/1.

He looked beaten when boxed in on the rail approaching the last quarter mile and when Carson had to switch to the outside of the field to obtain a clear run he was eight lengths behind the leaders.

At Epsom in June, Niniski started favourite for the Group One Coronation Cup, but after being held up by Carson in the early stages he was never able to get to the leader Sea Chimes and finished second, beaten two and a half lengths.

[9] In 1978 the independent Timeform organisation did not give Niniski a rating, but awarded him a "p", indicating that he was likely to make more than usual improvement, commenting that he would "do better over middle distances at 3 yrs".

[7] His other progeny included Hernando, Minster Son, Caitano (Premio Presidente della Repubblica, Aral-Pokal), Sapience (Ebor Handicap), Assessor, San Sebastian and the multiple Group One winner Lomitas (sire of Danedream).