London born Dean McDonald was aged 22 when he joined Rushden & Diamonds at the start of the 2008-09 season, having agreed a deal until the end of the season. He joined the club from Inverness Caledonian Thistle.

Having played for Arsenal at under-16 level, he joined the youth set up at Ipswich Town before making his Championship debut for the "Tractor Boys" in August 2005.

After a brief period on loan at Hartlepool United in November that year, he joined Gillingham at the start of the 2006 / 2007 season scoring 6 times in 29 appearances. He moved to Scotland last year to join Inverness Caledonian Thistle, but a change of management at the Scottish Premier League club saw him limited to appearances off the bench and he subsequently had his contract cancelled by mutual consent.

Manager Garry Hill commented on the signing "Dean started his career at Arsenal before playing for the first team at Gillingham and IpswichTown and subsequently Inverness.He has pace in abundance and can play either in wide areas or up front and will no doubt cause our opposition problems on the park this coming season."

After scoring a hat-trick on his debut in a Diamonds shirt in a friendly against Halstead Town, he scored the winner in a friendly against Championship Bristol City, and then made his senior debut on 26th July 2008 as a substitute in the Maunsell Cup Final against Peterborough United - scoring after 10 minutes, putting him as one of the top five fastest scorers for the Diamonds on their senior debut. He went on to make his league debut for the Diamonds in their 1-0 opening day victory over Eastbourne Borough on 9th August 2008. He scored his debut league goal against Kidderminster Harriers on 30th August 2008.