Neil Rock is back in the NCU after his proposed switch to Munster Reds was reversed.
The 20 year-old's return to Belfast had been on the cards once Gary Wilson retired to take up a coaching post with the Warriors, and with PJ Moor becoming available last month.
Rush left-hander Rock joined the Knights in 2018, and has gone on to play 28 times since across all formats.
Northern Knights wicket-keeper Neil Rock
“I’m delighted to be back with the Knights," said Rock. "They’re a great bunch of a lads and I’ve really enjoyed my time in Belfast
"Hopefully we can put a good run of performances together over the season and win some silverware.
“With Gary retiring, an opportunity opened up for me to return to the Knights. They’re big boots to fill but a challenge I’m looking forward to. I learned a lot from him in the last two seasons.”
Head Coach Simon Johnston was delighted to have a player of his calibre back in the fold.
“To have Neil back in our squad is excellent news.
“He has been a great player for us over the last few years and we can’t wait to have him back again for the 2021 Inter-Provincial Series.
“It was always in our long-term plans for him to take over from Gary when he retired so to have him back and behind the stumps is brilliant.”
Cricket Ireland are expected to announce the revised 50-overs interpro itinerary later this week once venues have been ratified.
More matches are being played in May to give the internationals more game time ahead of the three World Cup Super League matches in The Netherlands on June 2, 4 and 7.