Maguire started the year with a victory on 14 February in the Northrop Grumman Regional Challenge played at the 6,017-yard, par 71 Palos Verdes Golf Club. She finished joint first with rounds of 68, 71, 70 for her fifth college victory, also helping Duke to third place in the tournament. Maguire added her second victory of the year at the LSU Tiger Golf Classic held at University Club in Baton Rouge, Louisiana, USA on 26 March. She finished with a total of 206 after rounds of 67, 68, 71, which included an eagle. She also helped Duke University win the team title. In her seven tournaments of the 2016–17 college season, Maguire has only finished outside the top three places on one occasion. Her victory equalled the Duke University record of six individual wins held by Brittany Lang and Lindy Duncan. Maguire was selected as ACC Golfer of the Month for March 2017, which is the fifth time she has won the monthly award in her college golf career. Maguire won again on 15 April, claiming the ACC Championship for the second time in her career. She finished with a total of 210 after rounds of 68, 72 & 70 at the Reserve Golf Club in Pawleys Island, South Carolina, USA. She also helped Duke University to win the ACC team title. Maguire was selected as ACC Golfer of the Month for April 2017, which is the sixth time she has won the monthly award in her college golf career. On 11 May Maguire was voted the ACC Women’s Golfer of the Year for the second time in her career and was also selected for the All-ACC Women’s Golf Team for the third year in a row. On 11 May Maguire was selected for the College Sports Information Directors of America Academic All-District III Women’s At-Large Team, which recognises the nation’s top student-athletes for their combined performances athletically and in the classroom. On 23 May, Maguire was named the USA Women's Golf Coaches Association (WGCA) National Player of the Year for the second time in three years and became just the fifth player in history to win the award multiple times. She was also selected for the WGCA First Team All-Americans. Over 10 events in 2016–17, Maguire registered eight top-five placements, three victories, nine rounds in the 60s and 21 rounds of even or under par. She finished no lower than tied sixth over the course of the season including a Duke University and ACC all-time record 70.29 season stroke average, which is also the second lowest average in NCAA history after Lorena Ochoa's average of 70.13 in 2002. On 24 May Maguire was awarded the 2016-17 GolfStat Cup which is presented to the player with the best scoring average versus par with at least 20 full rounds played during a season. It was the second time in her career to win the cup. Maguire also finished in first place on the Golfweek/Sagarin women’s college end of season rankings. On 8 June Maguire won the Annika Award for the second time, becoming the only person to win it twice. She was also selected on the CoSIDA Academic All-America® Division I Women’s At-Large Team, only the second Duke golfer in history to be so. On 17 June Maguire won the British Ladies Amateur Golf Championship for the first time, beating Ainhoa Olarra of Spain 3 & 2 in the matchplay final held at the Pyle & Kenfig Golf Club, Waun-y-Mer, Wales. On 25 June Maguire was named the ACC Women's Golf Scholar-Athlete of the Year and was also named to the All-ACC Academic Team for the third year in a row. On 28 June Maguire won the Golfweek National Player of the Year award for the second time in her career and was also selected to Golfweek First Team All-America for the third straight season. On 6 July Maguire represented Great Britain & Ireland in the Vagliano Trophy against Europe, held at Circolo Golf Bogogno, Italy. Europe won 15 points to 9. Maguire contributed 1 point of the GB & Ireland total. On 5 July Maguire was selected for the Women’s Golf Coaches Association (WGCA) All-American Scholars Team for the third year in a row. On 10 July Maguire was awarded the 2017 Edith Cummings Munson Golf Award by the Women’s Golf Coaches Association (WGCA). She is only the second golfer in history to win both the Edith Cummings Munson Golf Award and the WGCA Player of the Year in the same season. On 6 August at the Kingsbarns Golf Links, Scotland, Maguire made the cut and was runner-up for the Smyth Salver awarded to the leading amateur at the Ricoh Women's British Open, one of the major professional championships, after rounds of 69, 71, 70, 75. On 15 August 2017, Maguire was awarded the Mark H. McCormack Medal given annually to the number one ranked female amateur golf player in the world. This is the third successive season Maguire has won the award thus equalling the all-time record holder Lydia Ko. On 12 September Maguire began the 2017-2018 College Golf season by winning the Jim West Challenge at The Fazio Course at The Club at Carlton Woods, The Woodlands, Texas, USA. Her rounds of 67, 63, 70 for a total of 200 included the lowest round of her career, a 63, which is the second lowest round in the history of Duke University, one stroke behind Liz Janangelo's 62. Maguire's 36-hole and 54-hole totals of 130 & 200 also broke the Duke all-time scoring records for two and three rounds. Her 13-under par total of 200 also broke the tournament all-time record. She also helped Duke win the team title at the tournament as well as setting a new school team scoring record of 33-under par total of 819. Duke also set a new Jim West Challenge tournament record for under par (-33) and 54-hole score (819). This is Maguire's fifth title of the calendar year 2017.[7] On 9 October Maguire was awarded the European Ladies' Amateur Golf Ranking's gold medal for the third successive year. On 11 October Maguire was selected as ACC Golfer of the Month for September 2017, which is the seventh time she has won the monthly award in her college golf career. She now holds the record for most ACC Golfer of the Month awards. Maguire won her second tournament of the 2017-18 college season and her sixth win of the calendar year 2017 at the Ruth's Chris Tar Heel Invite held at Chapel Hill, North Carolina on 15 October with rounds of 69, 66, 69. Her 12-under par total was a tournament record. She also helped Duke win the team title at the tournament. On 22 October, Maguire qualified to play in the professional Symetra Tour in 2018 by finishing in ninth place at the LPGA Qualifying Tournament (Stage II) with rounds of 70, 69, 70, 72. She finished as the second highest amateur. On 9 November Maguire was selected as ACC Golfer of the Month for November 2017, which is the eight time she has won the monthly award in her college golf career. On 27 November Maguire was named 2017 Global Golf Post Female Amateur of the Year.[8] She was also chosen as a member of the Global Golf Post All-Star amateur team of 2017, the third year in a row that she has been selected. On 21 December Maguire was named as the Irish Golf Writers' Women's Amateur of the Year for 2017, the fourth time she has won the award. On 26 December Maguire was named as AmateurGolf.com Women's Player of the Year for 2017, the second time she has won the award which means she is the joint record holder in the history of the award.