The satellite is to separate from the Briz-M upper stage at 00:31 GMT on October 22.
This will be the second Proton launch after an accident in May this year. The first successful launch took place on September 28 when the Russian Lutch satellite was orbited.
The Express-AM6 is a satellite that provides communications and broadcasting services in Russia. The lifetime of the spacecraft is 15 years.
The director general at Russian Satellite Communications Company, Yuri Prokhorov, said earlier the enterprise plans to add nine advanced communications satellites to its orbital grouping by 2020. Thus, the number of satellites will reach 20.