Walcott, 23, joined fellow England internationals Jack Wilshere, Alex Oxlade-Chamberlain, Kieran Gibbs and Carl Jenkinson as well as Wales midfielder Aaron Ramsey in tieing his future to the Gunners after finally signing an extension, said to be worth £100,000-a-week.
Having seen the likes of Cesc Fabregas, Samir Nasri and, last summer, Robin van Persie all move on in recent seasons, Wenger hopes Walcott can now go on to fulfil his undoubted potential at Emirates Stadium.
"Theo's contract extension now gives us a strong nucleus of ambitious young players who have committed to the club and want to be successful with us as a group," the Arsenal manager said.
"We are all delighted that Theo has signed a new contract. He joined us as a 16-year-old and since then has developed very well to become an extremely important player for both Arsenal and England."
Walcott is Arsenal's leading scorer this season with 14 goals, which includes two hat-tricks.
It had been suggested part of any new deal was subject to Arsenal meeting Walcott's desire to be deployed more in his preferred role as a central striker.
Gunners boss Wenger, though, last week insisted there was no such clause, and that he would never agree to tactical demands from any player.
Walcott was back on the flank for the midweek FA Cup third-round replay victory over Swansea, with France international Olivier Giroud leading the attack.
"Theo is a strong player and also a great person, and the combination of his ability and pace always make him such a valuable asset either from the flanks or down the middle," Wenger said.