Tony played his junior rugby league primarily as a halfback and hooker for Penshurst RSL JRLFC. He played his first game in first grade in Round 21 1995 for the St. George Dragons against the North Queensland Cowboys. The first try he ever scored came after four seasons. It was for the Bulldogs in the 1998 NRL Grand Final. Grimaldi also played briefly with Gateshead Thunder and Hull F.C. in the Super League competition. Tony Captained Hull F.C., due to his extensive experience in rugby league, to a final series. He then returned to the Canterbury Bulldogs in the 2002 season. He was not a regular first grade player over the 2002-2003 seasons, however he worked his way back to a starting position. Grimaldi was criticised for comments made in a press interview regarding Andrew Johns. Grimaldi was quoted as saying "I think you should be able to swear at the touchie if the decision's wrong." He later withdrew his comments attributing them to a "poor attempt at sarcastic humour." . In his player profile, when asked what his most memorable moment from his début was he replied: "I've had so many knocks to the head that I don't even remember what I had for breakfast." . Teammate Brent Sherwin cited Grimaldi as the team's biggest pest as "He once put chillies on a sandwich he bought for me.". This comedic approach differed greatly from that of his serious, professional, onfield attitude Tony is remembered as, "One of the club's workhorses,... rock solid in defence and a sound attacker. ". In his last season of first grade at almost 32yrs of age he still averaged over 40 tackles per game an amazing achievement considering the physically demanding nature of rugby. He featured in the premiership winning side of 2004 for the Bulldogs. In 2005 despite not making the finals Grimaldi was the NRL top tackler "In 2005 he was the NRL leading tackler with a whopping 852 tackles and many will remember his one-on-one steal against Broncos Karmichael Hunt back in Round 20 as the Bulldogs got home with a 29-22 victory." Tony captained the side on a number occasions when representative players were unavailable. As 2004 NRL premiers, the Bulldogs faced Super League IX champions, the Leeds Rhinos in the 2005 World Club Challenge. Grimaldi captained the Bulldogs at lock forward, scoring a try in their 32-39 loss. Tony's loyalty and long standing service to the club was rewarded with a job within the Bulldog's administration. He is also of Italian descent and was eligible to represent the Italy national rugby league team. Despite recently announcing an extension of his contract until 2007 Tony was forced to announce his retirement from rugby league on 14 September 2006. This was due to a bulging disk in his neck causing extreme pain in his neck and down along his right arm. He had previously had two vertebrae fused exacerbating his injury and increasing the chance of permanently injurying his neck if he continued to play. He currently is the head conditioner for the bulldogs
