There is one change on the replacements' bench with Rob Webber replacing Jamie George.
Also starting for England are Youngs' fellow Lions Dan Cole, Tom Youngs, Geoff Parling and Brad Barritt, while Mako Vunipola is on the replacements bench alongside Owen Farrell.
England Head Coach Stuart Lancaster said: "The squad is massively excited to start the World Cup. Everyone has worked incredibly hard over the last three months and we are ready.
"All the players have put their hand up in training and the internationals we have played this summer and we are blessed to have such a strong squad to select from against a skilful and powerful Fijian side.
"Friday will be a great occasion for the whole squad and for the country. We are in a unique position to be playing in a World Cup on home soil and to have the support of a nation behind the team. That support will be a massive factor and we don't underestimate its importance.
"I'd like to congratulate Ben Youngs on his achievement. To win 50 caps for your country in such a relatively short period of time is testament to Ben's dedication and commitment."
England (v Fiji, Twickenham Stadium, 8pm BST, Friday September 18, 2015)
15 Mike Brown (Harlequins, 39 caps)
14 Anthony Watson (Bath Rugby, 11 caps)
13 Jonathan Joseph (Bath Rugby, 13 caps)
12 Brad Barritt (Saracens, 23 caps)
11 Jonny May (Gloucester Rugby, 16 caps)
10 George Ford (Bath Rugby, 13 caps)
9 Ben Youngs (Leicester Tigers, 49 caps)
1 Joe Marler (Harlequins, 33 caps)
2 Tom Youngs (Leicester Tigers, 24 caps)
3 Dan Cole (Leicester Tigers, 52 caps)
4 Geoff Parling (Exeter Chiefs, 25 caps)
5 Courtney Lawes (Northampton Saints, 40 caps)
6 Tom Wood (Northampton Saints, 38 caps)
7 Chris Robshaw (capt, Harlequins, 39 caps)
8 Ben Morgan (Gloucester Rugby, 29 caps)
16 Rob Webber (Bath Rugby, 13 caps)
17 Mako Vunipola (Saracens, 23 caps)
18 Kieran Brookes (Northampton Saints, 12 caps)
19 Joe Launchbury (Wasps, 24 caps)
20 Billy Vunipola (Saracens, 19 caps)
21 Richard Wigglesworth (Saracens, 23 caps)
22 Owen Farrell (Saracens, 31 caps)
23 Sam Burgess (Bath Rugby, 2 caps)
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