It was a magnanimous gesture from Horner at the end of an emotional day for Sebastian Vettel, who celebrated his eighth win of the campaign.
Vettel now stands on the cusp of becoming the youngest driver in F1 history to clinch back-to-back titles, and to become a double world champion.
The 24-year-old German is now 112 points clear of his nearest rival in Ferrari’s Fernando Alonso, with Jenson Button and Red Bull team-mate Mark Webber 117 down, with Lewis Hamilton 126 off the pace.
“To win in Monza is a dream come true,” said Horner, whose team are 126 points ahead of McLaren in their bid for the constructors’ crown.
“It was a great day for the team and a phenomenal result at a track which, on paper, wasn’t supposed to be our best.
“Very sadly though, we lost a team member earlier in the week, Erin Pezzella, a young lady who has been with the team for four years. She lost a very brave fight against cancer and we would like to dedicate this result in her memory.”
Vettel’s only blemish was in losing top spot off the grid on the run down to the first corner chicane to Alonso.
Chaos ensued behind, however, as Vitantonio Liuzzi lost control of his Hispania and wiped out Renault’s Vitaly Petrov and the Mercedes of Nico Rosberg to bring out the safety car.
Once that returned, Vettel wasted no time in passing Alonso with a breathtaking move around the Curva Grande, and from that moment he was never troubled.
Looking down as thousands of fans thronged the main straight for the podium ceremony, Vettel lost control of his emotions.
“I thought, looking at the grandstands and seeing so many people – ignoring the colour of their shirt – life doesn’t get much better than this,” said Vettel.
Button was runner-up for the third consecutive year, Alonso was third, with Hamilton fourth.