The 39-year-old has won two Giro stages during his 17-year pro career and was also part of two team time trial-winning efforts.
He'll form part of Vincenzo Nibali's support squad at the race, which is set to run from October 3-25, and will ride a predominantly Italian calendar in the build-up to the Corsa Rosa.
"Pieter is going to the Giro and will mainly ride an Italian programme," Trek-Segafredo directeur sportif Steven de Jongh told Eurosport. "Now that all teams have such a full agenda of racing, it's nice that we have him here."
Weening only joined Trek-Segafredo on June 5, having been without a team for the early stages of the 2020 season before the COVID-19 pandemic. His previous team, Roompot-Charles, folded at the end of 2019.
With previous stints at Rabobank and GreenEdge under his belt, Weening brings a wealth of experience to the table for the US squad. Back in 2011, he won stage 5 on the gravel roads of Umbria and held pink for three days, while in 2014 he triumphed on the summit finish of Sestola.
Weening has also raced six Tours de France, taking a stage win in 2005, and four editions of the Vuelta a España. He'll head to an altitude camp with the team's other Giro competitors next month, while the Tour de France squad will train in France.
"We will head to altitude in mid-July," said De Jongh. "The riders who will do the Giro will train in Italy, and we're going to France with the riders who'll take part in the Tour."
While Weening heads to Italy with two-time race winner Nibali, Bauke Mollema and Richie Porte will lead Trek at the Tour. Both are doing well ahead of the season restart in August, said De Jongh.
"Richie had a hard time at the beginning of lockdown but he has been doing very well in recent weeks. We know that Bauke is super professional. He's also in good shape."
The team is set to make their return to racing at the Vuelta a Burgos in late July, while Nibali will start off at Strade Bianche on August 1.
Thank you for signing up to Cycling News. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.