Mealamu was spared an eight-week suspension due to his "exemplary disciplinary record" in 82 Tests for the All Blacks, who have 48 hours to appeal the verdict. Television footage of the incident showed Mealamu grabbing Moody by the jersey and then diving forward, making contact with the back of England captain Moody's head.
The IRB's citing commissioner John West charged Mealamu with contravening Law 10.4a, "striking with the head" and IRB judicial officer Lorne Crerar led last night's hearing in Glasgow, implementing the ban.
A statement read: "The judicial officer (JO) appointed by the IRB, Professor Lorne D Crerar, upheld the citing complaint against player Keven Mealamu, the New Zealand hooker, namely that the player struck an opponent, England No 7 Lewis Moody, with his head, contrary to Law 10.4a. The JO determined that it was an intentional act of foul play.
"The JO further determined a mid-range entry point in the IRB list of sanctions, namely eight weeks, but in the absence of aggravating factors together with compelling mitigating factors including the player's conduct at the hearing and his exemplary disciplinary record, reduced the suspension to four weeks. The player is accordingly suspended up to and including Saturday, 4 December, 2010. The player has the right of appeal."
Mealamu is now set to miss Saturday's match with Scotland at Murrayfield as well as the fixtures against Ireland in Dublin on 21 November and Wales in Cardiff a week later.
The 31-year-old was cited along with Tana Umaga for a spear tackle on Lions skipper Brian O'Driscoll early in the first Test of their 2005 tour, only to be cleared. He was frustrated by the verdict on this occasion and said: "I'm gutted to be honest, really disappointed. I don't feel the outcome shows what sort of person I am. I've played more than 100 Super games and 82 Tests and never had any foul play against me. I do take it personally. I'm not that sort of person."
Mealamu's ban means All Blacks coach Graham Henry is set to turn to uncapped Hawke's Bay hooker Hika Elliot when he names his XV for Murrayfield tomorrow. Andrew Hore is the other hooker in the squad, but is short of match practice following a shoulder injury.
All Blacks skipper Richie McCaw and full-back Mils Muliaina will equal the legendary Sean Fitzpatrick's record tally of 92 caps if, as seems likely, the pair are named in Henry's starting XV.