ESPN reported US PGA Tour players Lee and Steele will join DP World Tour standout Pieters in jumping to the Saudi-backed series, which has lured top talent with $25 million purses and 54-hole events.
Lee missed the cut at this week's PGA tournament at Riviera while Steele withdrew before the event began. Pieters, ranked 34th, didn't get an invitation.
Pieters, 31, figured to be set for a spot on Europe's Ryder Cup squad for this year's matchup with the United States in Italy. He is a six-time winner on the European tour, his most recent title coming last year at Abu Dhabi.
Lee, 32, was born in South Korea and became a New Zealand citizen in 2008. He won the European Tour's 2009 Johnnie Walker Classic as an amateur and took the US PGA's 2015 Greenbrier Classic.
Steele, 39, is a three-time PGA Tour winner, having taken the 2011 Texas Open and 2016 and 2017 Safeway Opens.
The moves are the latest in the split created when LIV Golf debuted last June, luring away such players as Dustin Johnson and Phil Mickelson.
The 14-event LIV Golf season opens on Friday at Mayakoba in Mexico.
