Midfielder Michael "Mickey" Spillane was a member of Norwich's Under-16 squad for the 2004/5 season. In January 2005, he was awarded a scholarship with Norwich to commence at the start of the 2005/6 season. He is equally at home at centre-back or in central midfield.

Spillane attended a training camp with the Republic of Ireland over the Christmas of 2004 and made his debut for the Republic's Under-17 team against Slovenia at Home Park in Dublin on Thursday February 18th 2005. Michael played all 90minutes as the Irish won 2-0.

After accompanying the first team squad on a number of occassions during the autumn and winter of 2005, Michael made his full debut for the injury-plagued Canaries as substitute in their FA Cup third round defeat at home to West Ham on 7th January 2006. he is the yougnest player to represent Norwich in the FA Cup.

In February 2006, Michael and Academy newcomer Mark O'Toole helped the Republic of Ireland Under-17s to second place in the Algarve Tourament - Michael scoring the only goal of the game between the Irish and hosts Portugal.

On 15th April 2006, Michael made his full debut for the Canaries in their 1-0 defeat at Sheffield Wednesday. He kept his place in the side for the 3-2 win over QPR two days later on Easter Monday.

On 30th June 2006, Michael signed a three-year professional contract with the Canaries.

Although out of the first team reckoning under Peter Grant during 2006/7, Michael was a regular for the Republic of ireland Under 18s, captaining them in a victorious international tournament in Portugal against the host nation, Belgium and Georgia. Michael scored the winner against Portugal and two goals in a 2-2 draw with Belgium. He was described by Irish coach Sean McCaffrey as "a key man for us in our Under-19s so he is captain of the Under-18s and he's very crucial for us.. He's always been terrific for us. He was brilliant against Holland recently and he is a very good player with great potential."

On 7th August 2008, Spillane and Chris Martin were loaned to Luton Town for the entirity of the 2008/9 season, days after they were omitted from City's first team squad photograph. His agent Paul Goddard believes his client's best interests are being served by the move - especially as Spillane is in the final year of his Norwich contract. He said: “Michael's been out of the picture for a little while now at City and this is a good opportunity for him to show what he can do. He needs to play and needs to develop.” However it will not be easy at Kennilworth Road. Luton lost their appeal against a 10-point deduction by the FA for financial irregularities, involving payments to agents. The decision means that Luton, who were also docked 20 points by the Football League for failing to comply with its insolvency policy, will start the 2008/9 season on minus 30 points.

Spillane was named the Football Association of Ireland's Under-19 Player of the Year in February 2009

Spillane however could not prevent Luton from being relegated on 13th April 2009 into the Conference following a goalless draw with Chesterfield. However he did play a key role as Luton won the Full Members Cup with a 3-2 win over Scunthorpe at Wembley.

Returning to Norwich, Spillane made 16 appearances, scoring once during 2009/10 as City went on to win the League One title. His goal against Leyton Orient was voted the goal of the season.

Apparently second-choice to Russell Martin, Spillane was allowed by Paul Lambert to sign for Brentford for an undisclosed fee on 1st July 2010

Out of favour at Brentford, Michael was allowed to train with Cambridge during November 2011. On 17th November, Spillane and West Ham striker Christian Montano joined Dagenham on loan until 3rd January 2012. Spillane made his debut, and was booked, in the 3-2 home defeat to Southend on 19th November 2011.

In early January 2012, Spillane and Brentford ended his contract by mutual consent and he signed permanently for Dagenham.

On 17th January 2013. Spillane moved eastwards signing for Southend for an undisclosed fee until the end of the 2012/13 season with an option fora further twelve months. "He's still a young player and is exactly the type of player I've been looking for during the window," boss Paul Sturrock told BBC Essex. "He's a hardworking midfielder who will hopefully enjoy huge success here with us. There were other clubs interested in taking Michael, but we're thrilled that he's decided to come here to play his football." He was not retained after the end of the 2012/13 season.

Spillane trained with Portsmouth in July 2013 but was sent away after his first day. He then trialled with both Aidy Boothroyd's Northampton and with Burton Albion before signing a one year contract with Cambridge United on 23rd August 2013. "I had other offers on the table, for more money, but I really believe in the project [here]," he said. "The fact that it's a new challenge appeals to me so it all meant there was only one choice - that was Cambridge United." He made 16 appearances for Cambridge before parting company on 31st January 2014. He trialled with St Johnstone before joining Sutton United on 14th March 2014. He made his debut the following day in a 4-0 win over Basingstoke Town with former Canary Dean Sinclair on the scoresheet.

On 26th September 2015, he became the eighth former Norwich player in the Lowestoft squad when he signed a two and a half year deal with the Crown Meadow side. He had played over 100 games for Sutton.

In early December 2016, he signed for Chelmsford City. In January 2020 he agreed to assist interim manager Robbie Simpson and was then appointed as Head of Academy in April 2020. He made 7 appearances during 2020/21 as he transitioned into a coaching role.