The gold medallist from the 2004 Athens Games won in 9.93 seconds ahead of compatriot Michael Rodgers (10.06) and Jamaica's Jacques Harvey (10.16).
Gatlin, the world indoor 60 metre champion who has enjoyed a revival of late after his four-year ban for doping ended in 2010, followed up his success in the Diamond League meeting in Doha on Saturday, where he beat Jamaica's Asafa Powell.
In the women's 100, Carmelita Jeter sprinted to victory in 11.11 seconds to finish ahead of Nigeria's Blessing Okagbare (11.21) and Aleen Bailey of Jamaica (11.34).
Jeter, who won the world title on the same track last year, was short of her season best of 10.81 but the American still extended her winning streak in finals to 10 races.
Another world champion who enjoyed a happy return to Daegu was Grenada's Kirani James, who won the men's 400 metres.
James finished almost a second ahead of Renny Quow of Trinidad & Tobago to claim victory in his first race of the season.
There was also success for America's world indoor 60 metre hurdles champion Aries Merritt (13.21), who pipped compatriot David Oliver (13.22) to win the men's 110 metres hurdles, while Ethiopia's indoor 800 world champion Mohammed Aman proved too strong over the distance to edge Kenya's Leonard Kirwa Kosencha.
Jamaican sprinter Sherone Simpson was disqualified in the women's 200 allowing American LaShauntea Moore to claim victory in 22.71, just ahead of her compatriot ChaRonda Williams.
Men's javelin world champion Matthias de Zordo of Germany only managed 79.39 metres in his season opener to finish a disappointing fourth in the event, which was won by Russia's Dmitri Tarabin with an 82.75 effort.
De Zordo will be among those athletes heading to Shanghai for this Saturday's second Diamond League meeting of the year.
1. Justin Gatlin (U.S.) 9.93
2. Michael Rodgers (U.S.) 10.06
3. Jacques Harvey (Jamaica) 10.16
1. Kirani James (Grenada) 44.72
2. Renny Quow (Trinidad and Tobago) 45.65
3. Calvin Smith (U.S.) 45.70
1. Mohammed Aman (Ethiopia) 1:43.51
2. Leonard Kirwa Kosencha (Kenya) 1:44.74
3. Andreas Bube (Denmark) 1:45.27
Men's 110m Hurdles
1. Aries Merritt (U.S.) 13.21
2. David Oliver (U.S.) 13.22
3. Jason Richardson (U.S.) 13.34
Men's 4 x 400m Relay
1. Japan 3:01.04
2. Australia 3:01.58
3. Australia B 3:07.29
Men's High Jump
1. Trevor Barry (Bahamas) 2.25
2. Jamie Nieto (U.S.) 2.22
3. Samson Oni (Britain) 2.22
Men's Long Jump
1. Ignisious Gaisah (Ghana) 7.99
2. Elvijs Misans (Latvia) 7.96
3. George Kitchens (U.S.) 7.92
Men's Shot Put
1. Ryan Whiting (U.S.) 21.14
2. Dylan Armstrong (Canada) 20.72
3. Adam Nelson (U.S.) 20.34
Men's Javelin Throw
1. Dmitri Tarabin (Russia) 85.75
2. Ari Mannio (Finland) 81.06
3. Igor Janik (Poland) 80.23
1. Carmelita Jeter (U.S.) 11.11
2. Blessing Okagbare (Nigeria) 11.21
3. Aleen Bailey (Jamaica) 11.34
1. LaShauntea Moore (U.S.) 22.71
2. ChaRonda Williams (U.S.) 22.82
3. Aleen Bailey (Jamaica) 23.15
1. Eunice Sum (Kenya) 4:05.99
2. Meskerem Assefa (Ethiopia) 4:06.52
3. Kaila McKnight (Australia) 4:06.54
Women's 100m Hurdles
1. Dawn Harper (U.S.) 12.65
2. Kellie Wells (U.S.) 12.66
3. Brigitte Foster-Hylton (Jamaica) 13.00
Women's Long Jump
1. Janay DeLoach (U.S.) 6.79
2. Karin Mey Melis (Turkey) 6.48
3. Saeko Okayama (Japan) 6.45
Women's Pole Vault
1. Anastasiya Savchenko (Russia) 4.60
2. Lacy Janson (U.S.) 4.50
3. Silke Spiegelburg (Germany) 4.45
Women's Hammer Throw
1. Betty Heidler (Germany) 77.24
2. Tatyana Lysenko (Russia) 76.14
3. Zhang Wenxiu (China) 75.68