Richarlison's goals were his first since joining Tottenham from Everton this summer
Marseille frustrated Spurs for large parts of this opening Group D game even after being reduced to 10 men early in the second half when Chancel Mbemba was sent off for a professional foul on Son Heung-min.
Spurs were struggling to make the breakthrough until Richarlison powered home a header from Ivan Perisic's cross with 14 minutes left to open his account following his £60m summer move from Everton.
Richarlison added another with an even better header five minutes later, this time meeting Pierre-Emile Hojbjerg's delivery at the far post to beat Marseille goalkeeper Pau Lopez and seal the points for Spurs.
Richarlison joined Spurs in order to sample the Champions League stage after making a huge contribution as Everton made a late escape from relegation last season.
The Brazilian was a hero at Goodison Park and - unusually for a big-money transfer - went with almost unanimous good wishes from supporters who had taken him to their hearts.
The 25-year-old was a powerful addition to the potent Spurs front line that already boasted England captain Harry Kane, Son and the talented Dejan Kulusevski - the sort of signing Conte craved in his hunt for major prizes.
He has had to bide his time but Richarlison's early contributions, including his contentious ball juggling in the recent win over Nottingham Forest, have already won him favour among Spurs fans.
And he cemented that status here with two vital goals that ensured Spurs came through a night of hard work with a crucial victory.
Richarlison's theatrics may occasionally irritate, but there is no doubting his quality and the two headers that made the difference here demonstrated exactly what he brings to Spurs.
Spurs may not have been pleasing on the eye at times this season but Conte has injected steel into the side that means they have the ability to get the job done even when they are not at their best.
It was the same here as they lacked rhythm and momentum for long periods, Marseille often the more composed side in possession until the sending-off of Mbemba.
He had to go and it handed the initiative to Spurs, who stuck to their task and ultimately found a match-winner in Richarlison.
Conte celebrated wildly on the touchline, the manner of victory seemingly giving him just as much pleasure as any earned by free-flowing football.
Spurs are a different beast under the fiercely driven Italian and here, even when not touching the heights, they proved it again.
-- Courtesy of BBC Sport