Keston Bledman was second while Jehue Gordon placed third at the 11th leg of the IAAF Diamond League, in Stockholm, Sweden, yesterday.
Bledman finished behind Jamaica's Nesta Carter in the men's 100m.
Carter was comfortably ahead in the Caribbean-dominated event with a season best 9.96 effort while being followed by Bledman, who grabbed second in a time of 10.09 seconds. Briton Chijindu Ujah and Nickel Ashmeade of Jamaica placed third and fourth, respectively, after both clocked 10.10 seconds. Diamond League 100m leader, USA's Michael Rodgers was disqualified after a false start.
Gordon, ranked sixth in the Diamond League 400m hurdles, ran 50.13 seconds behind runaway leader Michael Tinsley of the US (49.60 seconds) and Javiter Culson of Puerto Rico, who clocked 49.84.
Walcott took sixth in the men's javelin throw.
Walcott, who claimed silver at the Commonwealth Games earlier this month, threw an impressive 84.58m, less than a metre off his 85.28m personal best and national record. He completed five of his six attempts without fault but finished considerably behind the event winner Antti Ruuskanen of Finland, who threw 87.24m. Rohler Thomas (85.12) of Germany and another Finnish thrower Tero Pitkamaki (84.73), placed second and third, respectively.
The next leg of the Diamond League is carded for Birmingham, England, on Sunday.