The 25-year-old striker netted his first goal for new club Palermo in a 2-1 home win over Cremonese in the Coppa Italia second round on Sunday night.
Lafferty has now joined his Irish team-mates at their training camp ahead of the rearranged World Cup qualifier at Windsor Park.
He was banned for the 2-0 home defeat by Israel in March, and O'Neill is delighted to have him back in the fold.
Lafferty is yet to find the net in Group F, with Northern Ireland having drawn three and lost two of their qualifiers so far, but O'Neill has been pleased with his performances.
"Kyle's been great for me," he told Sky Sports News.
"He was suspended against Israel but his performances in the other games have been very good.
"It's another big game on Wednesday night and if selected, I expect another good performance."
O'Neill has lost the services of goalkeeper Alan Mannus after he damaged his shoulder playing for St Johnstone at the weekend, resulting in a call-up for Falkirk's Michael McGovern but says everyone else in his party is "fit and well".
Heavy snow in Belfast in March caused the postponement of the original scheduled fixture against Fabio Capello's Russia, and O'Neill admits a competitive game in August is far from ideal.
"This is the best of a couple of bad options," admitted O'Neill.
"We could have played on June 11, but that would have suited Russia a lot better.
"With this date, there's a lack of preparation time and we'll only get two days with the lads."