The British actors will both have guest roles in the hit US animated comedy and, according to Total Film, they will both play characters "cut from the same cloth".
No further information has been released about their roles.
Tom has recently lent his voice for another TV animation, 'Robot Chicken', in between shooting on Jim Jarmusch's vampire romance 'Only Loves Left Alive'.
Sean recently starred in fantasy drama 'Game of Thrones'.
It was recently revealed 'Modern Family' star Sophia Vergara had also landed a cameo role on 'Family Guy', appearing as main character Peter Griffin's sexual fantasy.
The curvy Columbian star will voice her own cartoon alter-ego when bumbling father Peter fantasises about the actress as he daydreams about being a telenovela star.
Sofia will also voice a woman selling roses in a restaurant in the same episode.
The eleventh series of 'Family Guy' - which is scheduled to air in the US from September 30 - will be star-studded with Johnny Depp, Ryan Reynolds, Elizabeth Banks and Kellan Lutz all scheduled to make an appearance.