Zajac will retire as a New Jersey Devil after signing a one-day contract with the club Monday.
Zajac scored a goal on his only shot and had three hits in Wednesday's 6-2 win over Boston in Game 6.
Zajac will suit up in Wednesday's Game 6 against Pittsburgh, Brian Compton of NHL.com reports.
Zajac has yet to dress for any of the playoff games versus the Penguins.
Zajac is a healthy scratch for Monday's game against Boston, Andrew Gross of Newsday reports.
Zajac was a healthy scratch for the first time as an Islander in the 1-0 shootout loss to the Capitals on Thursday, Neil Best of Newsday reports.
Zajac scored a goal on his only shot and added two hits in Thursday's 4-1 loss to Boston.
Zajac will be in the Islanders' lineup for Thursday's game versus Philadelphia.
Zajac could play Thursday versus the Flyers, Andrew Gross of Newsday reports.
The Devils traded Zajac and Kyle Palmieri to the Islanders on Wednesday for A.J. Greer, Mason Jobst, a 2021 first-round draft pick and a conditional 2022 fourth-round draft pick.