Farrell's squad includes nine Ulster representatives and 17 Leinster players, with just two Munster men (Tadhg Beirne and Craig Casey) and eight from Connacht. Andrew Porter, Ryan Baird, Mack Hansen and Tommy O'Brien all return after missing Ireland's summer matches against Australia, Japan and New Zealand.
Scrum-half Jamison Gibson-Park has been named despite not featuring for Leinster this season, while fly-half Jack Crowley, Jack Conan (shoulder), Harry Byrne, Iain Henderson, Paddy McCarthy, Calvin Nash and Bryn Ward are among those ruled out through injury.
Farrell said of the new call-ups: "It's always great to give people a chance for the first time. Jamie Benson came into camp with us in the summer before we went away, so it was great to get to know him and see what he's all about. But he started the season really well in a few different positions for Ulster, so that shows his versatility."
Of McNabney, who had previously been involved as a training panellist, Farrell added: "And James McNabney as well. We had him into camp on the 31st of August where we had an alignment camp, and that just goes to show that we've been interested in him for a while. He's some specimen of a man and he certainly runs his weight."
Benson, 24, can play at fly-half, centre or full-back and has made four appearances for Richie Murphy's side this season. McNabney, 23, missed the entire 2025/26 campaign before returning from an ACL injury over the summer.
Ireland begin their November series against Argentina at the Aviva Stadium on Friday, 6 November (8.10pm), before hosting Fiji on Saturday, 14 November (8.10pm) and South Africa on Saturday, 21 November (4.40pm). The Nations Championship Finals Weekend will take place a week later at the Allianz Stadium in London.
Ulster duo Zac Ward and Cormac Izuchukwu have missed out on selection, as has Munster prop Jeremy Loughman. The IRFU has also confirmed that an Ireland XV side will play three games in the coming months, starting against a Fiji A selection in Cork on 20 November.