The two-lap event had sadly been shorn of the sublime talents of the injured David Rudisha, the Kenyan who broke the world record in winning the Olympic title last year.
But, in his absence, Aman, the 19-year-old world indoor champion who has twice got the better of Rudisha, stepped into the void with some style.
"I'm the first Ethiopian to win a 800m gold medal!" Aman said. "This gold medal is a big thing for me and my country.
"It was not easy, a world championships final is such a hard race. All the athletes in the race were very strong and it's a double pleasure to be first in such company."
Aman added: "I was confident because I have speed on the last 100 metres and also nervous because it is the worlds and one has to be careful and smart.
"I didn't want to be boxed in like the semi-final so I just stayed patient when Symmonds and Solomon kicked off."
The race was bunched for all but the final 200 metres, fancied American Duane Solomon bossing his way into the front as Frenchman Pierre-Ambroise Bosse almost sideswiped Aman coming out of the first corner run in lanes.
At the bell, American Nick Symmonds came racing through, Aman again muscled out of the way and then boxed in behind the leading American duo.
The field spread with 200m to go in the run-in to the home strait. Symmonds went wide around Solomon, but Aman worked to go wider and outsprinted the American to the line for victory in 1min 43.31sec.
Symmonds held on for silver in 1:43.55, with a fast-advancing Ayanleh Souleiman claiming bronze in 1:43.76, a first medal for Djibouti since Ahmed Salah won silver in the marathon in the 1991 Tokyo worlds.
"I'm happy with my performance," said Symmonds. "I had a chance for gold and I hope some day I'll win it.
"The competition without Rudisha was like a gift on a silver plate and nobody wanted to waste the chance."
Souleiman said that "tonight all of Djibouti will celebrate because there hasn't been any medal since 25 years".
"I'm still in the 1500m on Wednesday and God willing I will win."
Solomon, who finished fourth in the London Olympic final in a time that in all previous finals would have seen him win a medal, faded to sixth behind Poland's Marcin Lewandowski and fifth-place Briton Andrew Osagie.
Fourth day finals results on Tuesday at the World Athletics Championships:
Men:
400 m:
1. LaShawn Merritt (USA) 43.74
2. Tony McQuay (USA) 44.40
3. Luguelin Santos (DOM) 44.52
4. Jonathan Borlee (BEL) 44.54
5. Pavel Maslak (CZE) 44.91
6. Yousef Ahmed Masrahi (KSA) 44.97
7. Kirani James (GRN) 44.99
8. Anderson Henriques (BRA) 45.03
800m:
1. Mohammed Aman (ETH) 1:43.31
2. Nick Symmonds (USA) 1:43.55
3. Ayanleh Souleiman (DJI) 1:43.76
4. Marcin Lewandowski (POL) 1:44.08
5. Andrew Osagie (GBR) 1:44.36
6. Duane Solomon (USA) 1:44.42
7. Pierre-Ambroise Bosse (FRA) 1:44.79
8. Abdulaziz Mohammed (KSA) 1:46.57
Discus:
1. Robert Harting (GER) 69.11
2. Piotr Malachowski (POL) 68.36
3. Gerd Kanter (EST) 65.19
4. Martin Wierig (GER) 65.02
5. Victor Hogan (RSA) 64.35
6. Robert Urbanek (POL) 64.32
7. Vikas Gowda (IND) 64.03
8. Victor Butenko (RUS) 63.38
9. Yennifer Frank Casaas (ESP) 62.89
10. Jorge Hernandez (CUB) 62.88
11. Julian Wruck (AUS) 62.40
12. Mario Pestano (ESP) 61.88
Women:
Pole vault:
1. Yelena Isinbayeva (RUS) 4.89
2. Jennifer Suhr (USA) 4.82
3. Yarisley Silva (CUB) 4.82
4. Silke Spiegelburg (GER) 4.75
5. Fabiana Murer (BRA) 4.65
5. Anastasia Savchenko (RUS) 4.65
7. Angelina Zhuk-Krasnova (RUS) 4.65
8. Jirina Ptacnikova-Svobodova (CZE) 4.55
8. Lisa Ryzih (GER) 4.55
10. Kristina Gadschiew (GER) 4.45
20km walk:
1. Elena Lashmanova (RUS) 1:27:08
2. Anisya Kirdyapkina (RUS) 1:27:11
3. Liu Hong (CHN) 1:28:10
4. Sun Huanhuan (CHN) 1:28:32
5. Elisa Rigaudo (ITA) 1:28:41
6. Beatriz Pascual (ESP) 1:29:00
7. Anezka Drahotov (CZE) 1:29:05
8. Ana Cabecinha (POR) 1:29:17
9. Julia Takacs (ESP) 1:29:25
10. Eleonora Giorgi (ITA) 1:30:01
3000m steeplechase:
1. Milcah Chemos Cheywa (KEN) 9:11.65
2. Lydia Chepkurui (KEN) 9:12.55
3. Sofia Assefa (ETH) 9:12.84
4. Hiwot Ayalew (ETH) 9:15.25
5. Etenesh Diro (ETH) 9:16.97
6. Hyvin Kiyeng Jepkemoi (KEN) 9:22.05
7. Valentyna Zhudina (UKR) 9:33.73
8. Antje Mldner-Schmidt (GER) 9:34.06
9. Gesa Felicitas Krause (GER) 9:37.11
10. Eilish McColgan (GBR) 9:37.33
Heptathlon:
2. Brianne Theisen (CAN) 6530
3. Dafne Schippers (NED) 6477
4. Claudia Rath (GER) 6462
5. Katarina Thompson (GBR) 6449
6. Sharon Day (USA) 6407
7. Eliska Klucinova (CZE) 6332
8. Antoinette Djimou (FRA) 6326
9. Karolina Tyminska (POL) 6270
10. Nadine Broersen (NED) 6224