Cave (foot) last featured over two months ago in the Heineken Cup win over Leicester Tigers and he will be a welcome addition to the midfield.
Muller's most recent outing in Ulster colours was the following week against Clermont Auvergne, before he suffered a calf injury in training.
Ulster will be without rested internationals Rory Best, Andrew Trimble and Stephen Ferris for the trip to Treviso, after the trio featured heavily for Ireland during their RBS 6 Nations campaign.
Simon Danielli is still struggling with injury and is not fit enough to be included in the province's panel, while Mike McComish is unavailable after suffering concussion during the Edinburgh match earlier this month. Jared Payne and Declan Fitzpatrick also remain sidelined.
There is also a place in the extended squad for Phoenix Academy second row Iain Henderson, who was a key player for the Ireland Under-20s this year, helping them to four wins in five Six Nations games.
Treviso are without a win in 2012, slipping to seven straight defeats in all competitions since the turn of the New Year. But Ulster will be wary of the threat posed by the Italians, after losing 23-12 to them at home earlier in the season.
Ulster's only defeat in their last six PRO12 encounters was 21-14 to the Cardiff Blues at the Arms Park on February 17.
The Ulstermen have scored 40 tries in this season's completion, a greater total than any other team in the league, and they will be looking to add to that tally on Saturday afternoon.
ULSTER Squad (v Benetton Treviso) - Backs (13): Paul Marshall, Ruan Pienaar, Ian Porter, Ian Humphreys, Luke Marshall, Ian Whitten, Nevin Spence, Darren Cave, Stefan Terblanche, Craig Gilroy, Conor Gaston, Chris Cochrane, Adam D'Arcy.
Forwards (19): Callum Black, Tom Court, Adam Macklin, John Afoa, Jerry Cronin, Paddy McAllister, Andi Kyriacou, Nigel Brady, Lewis Stevenson, Dan Tuohy, Johann Muller (capt), Iain Henderson, Tim Barker, Neil McComb, Willie Faloon, Pedrie Wannenburg, Ali Birch, Chris Henry, Robbie Diack.