The 20-year-old Mount played under new manager Frank Lampard on loan at Derby last season, and has impressed in recent weeks, becoming Chelsea’s top scorer in pre-season.
The kick-off was delayed 15 minutes due to fan congestion, as Lampard chose a strong team including new signing Christian Pulisic.
After striking the post through a Liam Moore header, Championship side Reading took the lead as Josh Barrett lobbed Willy Caballero having seen his initial effort blocked by Davide Zappacosta.
Chelsea responded with a fine goal of their own as Ross Barkley struck an unstoppable free kick past Joao Virginia, before Kenedy’s hopeful long-range shot took a deflection off Omar Richards and wrong-footed Virginia.
There were 20 changes at half time, but the goals kept coming as Michael Morrison tapped home for 2-2, before both sides struck the woodwork through David Luiz and Teddy Howe respectively.
Mount then got his first, driving past Sam Walker after good work from Tammy Abraham, and then moments later got another as Walker’s clearance hit Michy Batshuayi, allowing Mount to round off a fine day.
Reading scored the third through Sam Baldock with 20 minutes remaining, but Chelsea held on.